| Version 2.68 |
Almost all of TEX's mathematics is supported with the exception of a few obscure symbols that are absent from the fonts normally available to browsers. Support includes, for example, in-line equations with subscripts and superscripts, display equations with built-up fractions, over accents, large delimiters, operators with limits; matrix, pmatrix, cases, [but not bordermatrix]; over/underbrace [but using a rule, not a brace].
These cover most of the vital LATEX constructs. Internal hypertext cross-references are automatically generated (e.g. by ref and tableofcontents) provided LATEX has previously been run on the document and the appropriate command-line switch is used.
\epsfbox{file.[e]ps} Puts in an anchor called "Figure" linked to
file.[e]ps (default), or alternatively calls user-supplied script
to convert the [e]ps file to a gif image and optionally inline it.
\special{html:"tags"} inserts ``tags'' into the HTML e.g. for images etc.
\href{reference}{anchor} highlights ``anchor'' with href=``reference''.
\url{URL} like \href but with URL providing both reference and anchor.
\begin{[raw]html} ... \end{[raw]html} environment passed direct to output.
\tthdump{...} The group is omitted by tth. Define \tthdump as a nop for TeX.
%%tth:... The rest of the comment line is passed to tth (not TeX) for parsing.
When TTH encounters TEX constructs that it cannot handle either because there is no HTML equivalent, or because it is not clever enough, it tries to remove the mess they would otherwise cause in the HTML code, generally giving a warning of the action if it is not sure what it is doing. The following are not translated.
\magnification \magstep etc : Removes the whole construct. New or non-standard dimension tokens: removed. Boxes in equations other than a simple \mbox. \newbox, \unhbox, \raisebox, \lowerbox and similar usages.
The source for TTH is flex code which is processed to produce a C program tth.c which comprises the distribution. This file is compiled by
gcc -o tth tth.cor whatever C compiler you are using. Compilation takes a couple of minutes on a fast 486.
The executable should then be copied to whatever directory you want (preferably on your path of course). That's all!
Alternatively you may be able to obtain a precompiled executable from wherever you accessed this file. The Wind@ws executable comes with a batch file for installation. Just run it by the command ``install''.
Command line is as follows. The order of the parts is irrelevant. Switches (preceded by a minus sign -) can appear anywhere on the line. Square brackets should not be entered, they simply indicate optional parts of the command line.
tth [-a -c -d ... ] <file.tex [>file.html] [2>err]
-a automatic picture environment conversion using latex2gif (default omit).
-c prefix header "Content-type: text/HTML" (for direct web serving).
-d disable delimited definitions.
-e? epsfbox handling: -e1 convert figure to gif using user-supplied ps2gif.
-e2 convert and include inline. -e0 (default) no conversion, just ref.
-f? sets the depth of grouping to which fractions are constructed built-up
f5 (default) allows five levels built-up, f0 none, f9 lots.
-g don't guess an HTML equivalent for font definitions, just remove.
-h print help. -? print usage.
-i use italic as default math font.
-Lfile tells tth the base file (no extension) for LaTeX auxiliary input,
enables LaTeX commands (e.g. \frac) without a \documentclass line.
-ppath specify additional directories (path) to search for input files.
-r output raw HTML (no preamble or postlude) for inclusion in other HTML.
-r2 omit just the time stamp. -r1 is equivalent to -r.
-t display built-up items in textstyle equations (default in-line).
-w don't attempt HTML title construction or warn on failure. Default warn.
-xmakeindx specify a non-standard makeindex command line.
-v give verbose commentary.
The program is a filter, i.e. it reads from stdin and writes to stdout.
In addition, diagnostic messages concerning its detection of unknown
or untranslated constructs are sent to stderr. If these standard
channels are not redirected using < and >, then the
input is read from the command line, and both output and error
messages are printed on the screen.
TTH is extremely fast in default mode on any reasonable hardware. Conversion of even large TEX files should be a matter of a second or two. This makes it possible to use TTH in a CGI script to output HTML directly from TEX source if desired; (stderr may then need to be redirected.)
Messages about TTH's state and its assessment of the TEX it is translating are output always to the stderr stream, which normally displays on the console, but under Un*x type systems can be redirected to a file if necessary. Normally these messages are one of three types:
The switch -v causes more verbose messages to be output, which may be helpful for understanding why errors are reported. A higher level of verbosity -V can be invoked, but is intended primarily for internal debugging of TTH and will rarely be comprehensible!
The presumption that lies behind TTH message design is that the file being translated has been debugged using TEX or LATEX to remove syntax errors. TTH is not good at understanding or reporting TEX syntax errors and does not keep an exact count of line numbers (especially when \input is used). Therefore error reporting by TTH does not reach even the low standard of clarity set by TEX and LATEX error messages. Although TEX files can be debugged using TTH alone, since it is very fast, the process is not recommended for inexpert TEX users. Moreover, since TTH understands both TEX and LATEX simultaneously, it can parse some files that TEX or LATEX separately cannot.
Equations are translated internally into HTML3.2 as much as it allows. TTH uses HTML3.2 tables for layout of built-up fractions in display equations. It also uses the HTML tag < font face=``symbol'' > , part of the HTML4.0 specification, to render Greek and large delimiters etc. Untranslatable TEX math tokens are inserted verbatim.
The internal approach to equation translation is a major area where TTH departs from the philosophy of LATEX2html and its derivatives. TTH does not use any images to try to represent hard-to-translate constructs like equations. Instead it uses the native ability of HTML to the fullest in providing a semantically correct rendering of the equation. The aesthetic qualities obtained are in practice no worse on average than LATEX2html's inlined images, which are generally slightly misaligned and of uncertain scaling relative to the text. Some limitations in the HTML code are inevitable, of course, but one ends up with a compact representation that can be rendered directly by the browser without the visitor having to download any additional helper code (e.g. Java equation renderer).
TTH offers an option [-i] which makes italic the default font within equations, and thus the style more TEX-like. The italic font appearance in browsers is not as satisfactory as TEX's math italic, so for many documents roman looks better.
Spacing in equations is handled slightly differently by TTH than by TEX. The reason is that most browsers use fonts that will crowd the characters horizontally too close for comfort in many cases (for example: M||/2). Also, built-up HTML equations are more spread out vertically than in TEX. Therefore TTH equations look better if spaces are added between some characters. So TTH does not remove spaces in the original TEX file between characters in equations. The author is thus able to control this detail of layout in the HTML without messing up their TEX file - since TEX will ignore any spaces inserted. Legacy TEX code that contains a lot of spurious whitespace (ignored by TEX) may, as a result, occasionally become too spread-out when translated.
Some TEX capabilities are extremely difficult or impossible to translate into HTML, because of browser limitations, and are best avoided if possible. Arrays or matrices in in-line equations cannot be properly supported because tables cannot be placed in-line in HTML4. TTH output often will be strangely disjointed. Likewise built-up fractions, most over- and under-accents, and indeed anything that requires specific placement on the page other than simple subscript or superscript and underline, cannot be rendered in-line in HTML, although TTH will render them well in displaystyle. These latter constructs are nevertheless commonly used in in-line TEX. TTH adopts the default policy of indicating in an unambiguous and relatively intuitive way what construct is being used (as opposed to simply omitting it). For example $\hat{a}$ is rendered [^a]. The result is rarely elegant. Therefore in authoring TEX that is known to be destined for HTML translation, one should bear in mind these limitations, and use an appropriate style.
As an option, TTH provides switch -t to convert inline
equations that use built-up constructs into a sort of half display,
half in-line equation. Each time a new in-line equation is encountered
[$ ... $ or \( ... \)] that needs to be built up, an
HTML table that starts a new line is begun, and the text then flows on
afterwards. For example
| 1 2 + n |
Forward references in LATEX are handled by multiple passes that write auxiliary files. TTH does only a single pass through the source. If you want TTH to use LATEX constructs (e.g. tableofcontents, bibliographic commands, etc.) that depend on auxiliary files, then you do need to run LATEX on the code so that these files are generated. You must also tell TTH, using the switch -Lfilename, the base file name of these auxiliary files (which is the name of the original file omitting the extension). If TTH cannot find the relevant auxiliary file because you didn't run LATEX and generate the files or didn't include the switch, then it will omit the construct and warn you. Forward references via ref will not work if the .aux file is unavailable, but backward references will. The -L switch with no filename may be used to tell TTH that the document being translated is to be interpreted as a LATEX file even though it lacks the usual LATEX header commands. This may be useful for translating single equations that (unwisely) use the \frac command.
If you routinely use LATEX in a way that requires auxiliary files and grow tired of always having to specify the -L switch to TTH, a simple ``l2h'' script may be useful. For example under Linux (Un*x) a script such as
tth <$1.tex >$1.html -L$1may save some typing.
TTH supports bibliographies that are created by hand using \begin{thebibliography} etc. Such bibliographies do not require anything beyond the .aux file. TTH also supports bibliographies created using BibTEX from a biblography database. The filename.bbl file is input at the correct place in the document. However, this filename.bbl is not created automatically either by LATEX or TTH. In addition to running LATEX on the source file to create the auxiliary file, you must also execute bibtex filename in the same directory, to create the filename.bbl file, and then run LATEX again to get the references right. (This is, of course, no more than the standard procedure for using BibTEX with LATEX but it must be done if you want TTH to get your bibliography right). If you don't create the .bbl file, or if you create it somewhere else that TTH does not search, then naturally TTH won't find it.
Indexing an HTML document is different from indexing a printed document, because a printed index refers to page numbers, which have no meaning in HTML because there are no page breaks. TTH indexes LATEX documents by section number rather than by page; assuming, of course, that they have been prepared with index entries in the standard LATEX fashion.
When processing a LATEX file that contains the \makeindex command in its preamble, TTH will construct an appropriately cross-hyperlinked index that will be input when the command \printindex is encountered, which must be after all the index references \index{ ... } in the document. TTH does this independently of LATEX, but not of the subsidiary program makeindex that is normally used with LATEX to produce the final index ``file.ind''. TTH creates its index entries in a file with extension .tid (Tth InDex). Because of makeindex program limitations, TTH currently removes all the page-number formatting that is present in the index entry (but not the reference formatting). It also uses the section reference style ``1-2'', separated by a dash, because this is the standard form that makeindex expects and it is cumbersome to change it. The actual reference is less important to the reader than the fact that TTH inserts a link to the actual place in the document indexed. When the \printindex command is encountered, TTH closes this file and runs makeindex on it, which creates by default a file with extension .ind, and then TTH reads the .ind file in as its index. Because the .ind file that TTH produces may well be incompatible with running LATEX itself on the file, TTH deletes the .ind file that it creates (and hence one is left without such a file at the end). If, instead of creating an index file during TTH processing, one wants to use with TTH an index file already created, all that is needed is to remove the \makeindex command from the top of the LATEX source. Any existing .ind file will still be input by \printindex but no indexing files will be written or deleted.
If you run TTH on a file that contains both a \makeindex command and a \printindex it will overwrite your file.ind. In the unusual situation where your index, file.ind, was created laboriously by hand and cannot be recreated, you should be very careful to remove the \makeindex command from the .tex file. For safety, of course, also save a copy of your file.ind somewhere else.
The \makeindex command, if present, will also cause TTH to add a linked entry called ``Index'' to the end of any table of contents. This entry is a highly desirable feature for an HTML file, but if there is no \printindex command at the end of the document, the index will not exist, so the reference will be non-existent.
On some operating systems with file name length restrictions, the makeindex program is called makeindx. Therefore a TTH switch is provided: -xcommandline, which substitutes commandline for the default call makeindex. Therefore, -xmakeindx will switch to the correct program name on one of these limited operating systems. This switch also allows additional parameters or switches to be passed to makeindex via e.g. -x"makeindex -s style.sty". If you don't have the makeindex program, you can't create indexes with TTH or LATEX, except by hand.
All of the index file processing naturally requires that TTH have write permission for the directory in which the original LATEX file (specified by the -L switch) resides.
Optionally TTH can use a more appropriate graphics format, possibly using a user-supplied (script or) program called ps2png or ps2gif to convert the postscript file to a png5 or gif file, ``file.png'' or ``file.gif''. [``file'' is the name of the original postscript file without the extension and png or gif are interchangeable as far as matters for this description]. When the switch -e1 or -e2 is specified, if ``file.png'', ``file.gif'' or ``file.jpg'' already exists in the same directory as implied by the reference to ``file.ps'' then no conversion is done and the file found is used instead. That graphics file is then automatically either linked (-e1) or inlined (-e2) in the document. If no such file is found, TTH tries to find a postscript file with extension that starts either .ps or .eps and convert it, first using ps2png then, if unsuccessful, ps2gif. Linux (un*x) ps2png and ps2gif scripts using Ghostscript and the netpbm utilities for this purpose are included with the distribution. A comparable batch program can be constructed to work under other operating systems 6 or else the conversion can be done by hand. Naturally you need these utility programs or their equivalent on your system to do the conversion. The calling command-line for whatever ps2png (or gif) is supplied must be of the form:
ps2png inputfile.ext outputfile.extThe program must have permission to write the outputfile (file.png) in the directory in which the file.ps resides.
By popular request, a third graphics option -e3 for generating icons is now available. If no previously translated graphics file, e.g. ``file.png'' exists, TTH passes to ps2gif (or png) a third argument consisting of the name, ``file_icon.gif'', of an icon file. ps2gif is expected to create it from the same postscript file. In other words the call becomes
ps2gif file.eps file.gif file_icon.gifThis third argument is then the file that is inlined, while the larger gif file named ``file.gif'' is linked such that clicking on the icon displays the full-size gif file. The icon will not be created if ``file.gif'' already exists, because ps2gif will not then be called.
The LATEX2e command \includegraphics{...} and the older \[e]psfig{file=...} are treated the same as \epsfbox. Their optional arguments are ignored.
If the extension is omitted for the graphics file specification, then .ps or .eps is tried. If the extension of the file specified is non-null and not .ps or .eps, no conversion is done but the file is referenced or in-lined as an image. In effect, then, TTH supports postscript, encapsulated postscript, gif, and jpeg, plus any future formats that become supported by common browsers. However, LATEX does not support these other formats, so it will give an error message if it can't find a postscript file, unless you specify the bounding box, thus preventing LATEX interrogating the file.
Boxes, dimensions, and fills are rarely appropriate for web documents because they imply an attempt to control the fine details of layout. Browsers make their own choices about layout of a document in HTML. For example they make the lines fit whatever size of window happens to be present. This dynamic formatting makes mincemeat of most detailed TEX layout. Therefore the best advice is to avoid these constructions as far as possible.
There are nevertheless many cases when a TEX document containing boxes, dimensions, and fills needs to be translated. Earlier versions of TTH made a point of trying to intercept the dimensions and drop them, so as not to clutter the HTML with rubbish. From version 2.5 onwards, limited translation of these constructs is supported. They are translated, where appropriate and possible, into HTML tables with widths and vertical skips estimated to give a reasonable result on a browser. It must be stressed that accurate translation is inherently impossible because browsers deal in pixel sizes and default font sizes that vary and are out of the control of the publisher.
The types of box usage that translate quite well are when things like
\hbox to \hsize{The left \hfil the Right}
\vbox{\hsize=2in Matter to be set in horizontal mode to a
limited hsize}
\makebox[0.6\hsize][r]{Stuff to the right of the makebox.}
\framebox{check}
are on a line by themselves.
You get:
| The left | the Right |
| Matter to be set in horizontal mode to a limited hsize |
| Stuff to the right of the makebox. |
| check |
Usages that translate poorly tend to be boxes within a line of text. That is because current HTML table implementations have to start a new line unless they happen to be adjacent to a table already. Thus an hbox in a line will give a line break that you might not have wanted. This behaviour is really a bug in the browsers, but we are currently stuck with it. The behaviour of HTML tables is buggy [see 11.6] when their alignment is specified, which means that strange results are likely if more than one box on a line is being set. Boxes in equations are troublesome. The only type that is reasonably supported is \mbox which is often used in LATEX for introducing text inside equations.
Usages that are currently not supported at all include negative skips, \newbox,\newdimen, anything that trys to \setbox,\unhbox,\unhcopy, and indeed any storage of boxed material.
The only important dimension parameter that is currently supported is \hsize. This can be reset using the plain TEX format e.g. \hsize = 3in but only within a group, because it makes no sense for the HTML file to try to specify the width of the line at the outermost level, which is the browser's business.
TTH trys valiantly to mimic the sort of text alignment that is obtained using glue such as \hfil and \hss, provided it is inside a box. However, the alignment algorithm of HTML tables makes it impossible to obtain fills with exactly equal sizes. So don't be surprised if some results looks disagreeable. Moreover, TTH will completely ignore the glue outside an hbox, and it doesn't know the difference between \hfil and \hfill, etc.
Delimited parameter definitions are fully supported. However, macros in some style files are written in such a way that the recognition of the delimited parameter depends on other TEX behaviour (e.g. dimensions) that are not supported by TTH. In such cases it is all too possible for the delimited parameter not to be matched, resulting in a runaway argument situation. Thus, delimited parameter macros are especially dangerous when using TTH, or indeed any process other than TEX itself. (And they are never exactly ``safe TEX''). The recognition of these definitions can be disabled using the -d switch, in which case the definitions are simply discarded.
Conditionals such as \if, \ifnum and so on are
supported, as listed above (1.1.2). In TTH they have one
syntax limitation. Further `if' commands are not permitted in, or as part of
a command expanded in, the tokens, characters, or numbers being
tested. Thus, an example of truly perverse usage such as
\ifnum 1=\if ab 1\else 2\fi True \else False \fi
will likely
break. Nested `if' constructs are permitted in the conditional
text, however, so
\ifnum 1=1 True\if ab -true\else -false\fi \else False \fi
is fine.
Because TTH does not internally resemble TEX, whereas the result of
conditionals such as \if and \ifx may depend on internal
representations, there cannot be 100% compatibility of such tests at
the lowest level. Still, tests on externally defined commands ought
generally to give correct results. When authoring documents in TEX one
is generally well advised to avoid conditionals.
Although TTH supports a remarkably complete subset of LATEX, it does not support all of the complicated primitive details of TEX, partly because that would be unnecessary. For example, practically any TEX that redefines category codes (other than @ which TTH treats universally as a letter) will break because TTH knows nothing about the concept of category codes. (If you don't know much either, about this unfortunate aspect of TEX, join the vast majority of TEX users!) A related example is that TTH expects only letters or @ in user-defined command names, not punctuation characters etc.
TTH will find an input file if
Paths are searched in this order until an appropriate file is found or all directory options are exhausted
This policy provides a mechanism for making available the alternative package for TTH, without alteration of the original TEXfiles, by placing the (simplified) version of the macro package on the path TTH searches. An example using the -p switch might be
tth >file.html <file.tex -p/usr/local/tthinputs:~/mytthinputs
Since it is impossible to anticipate all style file incompatibilities, it must be the responsibility of the user (or the journal) to decide how to translate the concepts implemented in the original complicated macro package into simpler, TTH-compatible, TEXmacros.
Unrecognized or undefined commands of the form \dothis{one}{two}{three}, are treated by discarding all the following adjacent brace groups. A space between the close and open braces will terminate the discarded arguments and cause the following brace group(s) to be scanned as if just the text. This makes it possible to use formatting to make TEX code come out right in both TEX and HTML. For example if TTH encounters a command written ``\boxthis{width} {boxed material}'' which might be designed in TEX to provide a width to a defined command, written with a space after the first argument, it will ignore the width and scan the boxed material into the text.
In TTH (unlike TEX) most internal commands can not normally be redefined; any redefinition will simply be ignored (except inside edef and a few other places). This prevents TTH from safely allowing use of major packages that redefine standard TEX commands. For example amsTEX redefines footnote to have just one argument, which will cause problems. This particular example is potentially a problem with LATEX too, which also redefines footnote. TTH handles this by keeping track of whether the file is LATEX or TEX; therefore you should not mix the two dialects in a single file even though there is no need to tell TTH explicitly which type the file is. (Besides, a mixed file will play havoc with TEX itself.)
The LATEX syntax is recommended because the 68 standard named colors8 are directly supported internally by TTH using the named model. Any numerical CMYK, RGB and Gray color can also be prescribed. For example the following commands are enclosed in themselves: \textcolor[named]{BrickRed}{...}, \textcolor[rgb]{0.,.5,0.}{...}, \textcolor[cmyk]{0.,.5,0.,0.3}{...}. You can define custom colors in the usual way using, for example
{\definecolor{Puce}{rgb}{1.,.5,.8}
\color{Puce} This is my own Puce.}
Which gives ``
This is my own Puce.''
The command \pagecolor is supported but discouraged. It is highly likely to give rise to an HTML file that will fail validation because it inserts an HTML tag <body bgcolor=...> which will not be in its correct position (immediately following the title). The only way to be certain to produce an HTML file that passes validation is to put the title and body commands in by hand, using e.g. \special{html:<title>...</title><body ...>} Netscape seems not to mind a body tag out of order, but only the first one is able to set the page background color.
The commands \colorbox and \fcolorbox are supported via CSS style sheet commands. They will only work to set the background color of included text if the browser is set to use style sheets. ``This sentence'' is the result of the command \colorbox{green}{``This sentence''}. If it is colored, then your browser supports style sheets to this extent. If not, check your preferences settings.
The Plain TEX syntax using commands such as \Red{red text} requires the file colordvi.tex to be input prior to their use. But because TTH does not search the standard TEX paths, that file will not usually be found unless the full path is explicitly specified. If the file is not found, only the 8 standard colors
\Red, \Green, \Blue, \Cyan, \Magenta, \Yellow, \Black, and \Whiteare recognized internally by TTH. You can use the user-defined CMYK numeric style
\Color{0. .5 .5 0.}{pale red}
without the colordvi
file. It gives the result ``pale red'' but the
notation becomes cumbersome unless you define your color
e.g. like
\def\redcolor{0. .5 .5 0.}
\Color{\redcolor}{The stuff that is red.}
Another difficulty with the colordvi command \textColor (which is the color switch - LATEX syntax reversed that usage and changed to comma-delimited arguments just to confuse us) is that it is a global setting. It then becomes almost impossible to maintain proper nesting of the closure of the font commands used for colors in HTML. As a result, use of \textColor often gives HTML files that won't pass HTML validation.
TTH translates TEX into standard HTML and takes account as far as possible of the idiosyncrasies of the major browsers. Nevertheless, there are several problems that are associated with the browsers. Authors and publishers should recognize that these are not TTH bugs.
The characters with codes higher than 127 in the Mac fonts are in a different order from the standard ISO-8859-1 (sometimes called ISO Latin-1). If Netscape or IE on Macs have their document encoding set to the standard, then in versions 3 onwards they are programmed to access the glyph where they think the corresponding accented Latin character will be in the Mac font. This is fine if one really wants an accented Latin character. However, for mathematics, using the symbol font (which is ordered the SAME on the Mac as on other platforms) the result is that one gets the wrong symbol glyph. This is a particular problem with large delimiters. The fix is that the Mac browser must be set to use the Options/Document-encoding ``MacRoman". This tells the browser not to do the permutation to access the accented Latin characters in the Mac places; hence, for eight-bit characters, it accesses the symbol font correctly. This would break the Latin accented characters except for the fact that (most current versions of) the browsers still access characters in the Mac order if they are specified numerically using the HTML syntax ``&#???;". So TTH documents will in most cases display both accented characters and symbols correctly on Macs if the document-encoding is set to MacRoman.
In addition, NS4.0 has under Edit Preferences Fonts a choice between ``use document fonts'' and ``use my fonts overriding document''. You need to set ``use document fonts''. This necessity is obvious if you think about it. You can make any document into garbage by specifying your own font (e.g. Greek or Cyrilic) that happens not to be what the document is written in. The same is true for the symbols of mathematics. The reader must permit the document to specify the font. Browsers should always set ``use document fonts'' as the default.
In summary, you might want to tell people viewing your documents to set their browsers to View Encoding MacRoman, and Edit Preferences Fonts Use-document-fonts (NS 4.0).
[Unconfirmed reports indicate that P*gemill has problems of the same type.]
Symbol fonts are not normally enabled for Netscape running under X, because of the way Netscape groups its fonts. A fix for this is to install some aliases in the fonts directories or else to add a line to your .Xdefaults file. See http://hutchinson.belmont.ma.us/tth/Xfonts.html. You might want to put these notes on your site for people viewing your documents.
A font rendering problem exists for small size single-symbol overbar in the Xfree86 server. The overbar symbol may or may not appear, depending on the direction in which its window uncovered. (Yes, this is a really bizarre bug but can be demonstrated with the xfd program.) It is strictly not a Netscape bug but an X-server, or perhaps font, bug. This symbol is used by TTH only as a fall-back for \bar in situations like in-line equations where it can't render the construct using tables.
In Netscape 3.0 and 4.x under X, for example, the printing fonts are hard coded into the browser and the font-changing commands are ignored when printing. For that reason, visitors viewing TTH documents will often not be able to print readable versions of documents with lots of mathematics. This problem could, and should, be fixed in the browsers. However, if you want your readers to be able to print a high-quality paper copy of the file, then you probably want to make available to them either the TEX source or a common page-description format such as Postscript or PDF. Since HTML documents download and display so much faster and better than these other formats on the screen, TTH's translation provides the natural medium for people to browse, but not necessarily the best medium for paper production.
Under Wind*ws, both Netscape (3.0) and Internet Expl*rer (3.02) incorrectly size or space vertically the symbol glyphs so that small gaps appear between the parts of large symbols and delimiters. This occurs only at certain font sizes (different between the two browsers!) but causes a slightly annoying degradation of the appearance.
Both Netscape and IE fail (although somewhat differently) to carry font changing commands from cell to cell of HTML3.2 tables. In rendering equations (using tables) TTH circumvents this bug at the cost of significant extra effort and slightly verbose HTML. However, for tables generated by \halign or \begin{tabular} TTH takes no special steps to avoid this bug. Therefore you cannot, for example, increase the font size of an entire table by enclosing it in {\large ... } and indeed the table will revert to the default size even if it is inside a different sized section of text. Moreover, a change of font face in a cell, for example by \it will not carry over to the next cell. A document containing this problem will not pass some HTML validations. It is prevented if every cell of a TEX table is enclosed in braces and the required style applied separately to every cell - a serious annoyance.
IE can become confused about its vertical alignment in tables, with the result that symbols float above or below the horizontal line in built-up equations. This sometimes fixes itself if you simply refresh the page!
Tables embedded within a line of text, even if placed inside a span element, are incorrectly positioned. They generally force a new line. This is quite a significant handicap when translating in-line material that requires a table.
Nested tables in Netscape 4.x are not properly cleared by the <br clear=all> attribute. It appears that the next line is shifted down only by the height of the last innermost table in the nest. If this happens not to be the tallest table, the subsequent text will overwrite that tallest table. This sometimes the cause of problems when putting more than one box on a line.
On Macintosh Netscape, the standard HTML entity × for a multiplication sign is not recognised. There seems to be no good reason for this omission. Complain to the browser manufacturer!
One reason for violation arises because HTML4.0 requires a <title>...</title> for every document. A title is constructed from LATEX files that contain the \title{...} command, in which case HTML conformance is ensured by putting the \title command before any text (i.e. in the preamble, where it belongs). If the \title command is not desired in the TEX file, for example because it is a plain TEX document, a title can be provided by the author for the HTML document by putting a line like this at the top of the TEX file.
%%tth:\begin{html}<title>Put the title here</title>\end{html}
This line will be ignored by TEX. Actually, any raw HTML output at the
start of the file is assumed by TTH to indicate that the author has
explicitly output a title. If no title indication of any of the above
types is present, TTH attempts to construct a title from the first few
plain words in the document, in much the way that the first line can
become the title of a hymn. If commands like
\beginsection that output material to the HTML file occur
before the title has been constructed, the HTML title command will be
out of order and the formal standard will be violated. (See the FAQ
[B] for discussion of <head> and <body>.)
In the case where the title construction fails, or if some other TEX usage causes a violation of the formal standard, browsers will still render the output correctly if this manual is followed.
Known limitations are significant but mostly covered above. I would be interested to hear about bugs but only if reports are accompanied by the brief section of TEX code that causes the problem. Ungraceful failures to parse straightforward TEX code are of most interest. Aesthetic critiques (with TEX code) will be considered for future improvements. Failures on complicated macros are to be expected. It is now very difficult to crash TTH by exceeding array bounds. I would like to hear about it if you succeed, especially if the code gives no error with TEX. I would be glad to receive LATEX2e files (emailed to hutch@psfc.mit.edu) that illustrate LATEX bugs. But please don't send LATEX2.09 files or files that do not conform to the latest (1994) LATEX users' guide. And please check in the FAQ (B) first.
The code has been compiled and run on Linux 2.0, 2.2, MSDOS, Open VMS, and sundry other operating systems. See http://hutchinson.belmont.ma.us/tth/platform.html.
TTH is copyright © Ian Hutchinson, 1997-2000 (hutch@psfc.mit.edu).
You may freely use this software for non-commercial purposes. It may not be used for commercial purposes without an additional license. If you distribute any copies, you must include this file and these conditions must apply to the recipient. No warranty of fitness for any purpose whatever is given, intended, or implied. You use this software entirely at your own risk. If you choose to use TTH, by your actions you acknowledge that any direct or consequential damage whatever is your responsibility, not mine.
Many thanks for useful discussions and input to Robert Curtis, Ken Yap, Paul Gomme, Michael Sanders, Michael Patra, Bryan Anderson, Wolfram Gloger, Ray Mines, John Murdie, David Johnson, Jonathan Barron, Michael Hirsch, Jon Nimmo, Alan Flavell, Ron Kumon, Magne Rudshaug, Rick Mabry, Andrew Trevorrow, Guy Albertelli II, and for bug reports from others too numerous to mention.
The following macro definitions, although not needed for TTH, will enable a TEX file that uses the non-standard TTH commands to be correctly parsed by Plain TEX.
\def\hyperlink#1#2{\special{html:<a href="\##1">}#2\special{html:</a>}}
% Incorrect link name in \TeX\ because # can't be passed properly to a special.
\def\hypertarget#1#2{\special{html:<a name="#1">}#2\special{html:</a>}}
\long\def\tthdump#1{#1} % Do nothing. The following are not done for TtH.
\tthdump{%
\def\title#1{\bgroup\leftskip 0 pt plus1fill \rightskip 0 pt plus1fill
\pretolerance=100000 \lefthyphenmin=20 \righthyphenmin=20
\noindent #1 \par\egroup}% Centers a possibly multi-line title.
\let\author=\title % Actually smaller font than title in \LaTeX.
\input epsf % PD package defines \epsfbox for figure inclusion
% Macro for http reference inclusion, per hypertex.
\def\href#1#2{\special{html:<a href="#1">}#2\special{html:</a>}}
\def\urlend#1{#1\endgroup}
\def\url{\begingroup \tt
\catcode`\_=13 % Don't know why this works.
\catcode`\~=11 \catcode`\#=11 \catcode`\^=11
\catcode`\$=11 \catcode`\&=11 \catcode`\%=11
\urlend}% \url for plain \TeX.
}
Why won't TTH run under DOS? Something about DPMI.
It will, but the distributed DOS executable needs DPMI memory
extension support to run. Plain old DOS doesn't have that unless you
specifically load it. All Wind*ws versions from 3.1 on support it at
the DOS prompt.
Why won't TTH run from Program Manager in Wind*ws?
You need a command line. Call up the DOS prompt.
TTH does not recognize tableofcontents, backward
references, listoffigures, ...
Yes it does, see section 6.1, and use the -L switch.
TTH does not insert my picture environments.
If picture environment pictures are to be included, conversion to a gif file
is needed. See 6.5.
TTH messes up my tabbing environment.
Tabbing is not currently supported. It is alien to the HTML document
mark-up approach. See section 7.
How do I make TTH border my tabular table?
TTH looks in the format string argument of the begin{tabular}
environment and if it begins with a | (vertical bar) then the HTML
table is bordered.
TTH inserts the title and author even without the
maketitle command
True, TTH inserts them when you define them. This gives you a chance
to fine-tune the presentation if you wish.
Why doesn't \frac work in equations?
It does, but only in LATEX documents because \frac is not a
plain TEX command. The document you are presenting to TTH doubtless
has no \documentclass command and other LATEX blurb at the top.
If you insist on having LATEX commands available in such a document,
you can use the -L switch. But note that other changes in
interpretation (e.g. in footnotes) are implied by using this switch to
tell TTH that this is a LATEX file.
What is this strange result using \dot
\hat \tilde \frac
\vec ... in in-line equations?
Neither over and under accents nor built-up constructs such as
fractions can be rendered in-line (i.e. in a textstyle equation
produced by $ ... $) in HTML. Therefore, TTH outputs something that is
not elegant but reasonably indicates the original
intention. Additional brackets are inserted to ensure that fractions
are unambiguous. TTH will render all these built-up constructs
correctly in a display equation. See also 5.2 for an option.
Why does the large square root sign look so ugly?
There are some things that browser symbol fonts can't do well.
Why does a dagger sign come out strange?
Browsers don't generally have a dagger sign in their fonts. TTH uses a
kludge.
How do I insert code that is used only by TTH, not TEX?
Use %%tth: followed by the material you wish to pass to TTH.
TEX omits this line as a comment. Alternatively, insert \newif\iftth
at the top of your document, then use a conditional:
\iftth \TtH\ material \fi. TtH recognizes \iftth as a
special `if' that is always true, whereas to TEX it is simply a
new `if', which by default is false when defined.
How do I insert HTML tags into my file without TEX knowing?
Use %%tth: then on this line put
\begin{html} tags \end{html}. Do not try to continue this
html onto a second line with a second %%tth: before the
\end{HTML} because the html environment will output the
%%tth:, which it probably not what you want. Another way to
pass codes directly to the output is the \special{html: ... }
command. Do
not use \begin{verbatim} to pass HTML tags. It will
convert the greater than and less than signs to make them appear in
the display and not be interpreted as tags.
How do I insert code that is used only by TEX, not TTH?
Insert \newif\iftth at the top of the file and then use
the conditional constr
uction:
\iftth\beginsection{The \TtH\ Header}\par\else\beginsection{The \TeX\ Header}\fi
The `else' clause may also be used with a blank first clause, of
course: \iftth\else ... \fi.
Alternatively, insert the definition \def\tthdump#1{#1} at the
top of the file and then use \tthdump{\TeX\ material} to pass
stuff only to TEX. The command \tthdump is an internal command
for TTH (which cannot be redefined) that simply discards its argument.
Thus, for example, the following will output
alternate versions from TEX and TTH.
\def\tthdump#1{#1}
%%tth:\begin{html}<H1>The HTML Header</H1>\end{html}
\tthdump{\beginsection{The \TeX\ Header}\par}
How do I include the style file ...sty for the TEX paper I prepared for... journal?
If you are wise, you probably don't. TTH often can't handle
complicated journal formats for [La]TEX without modification, because
they frequently use newdimens, newboxes, category code modification or
other unsupported constructs. Instead, look at your TEX file, or the
TTH messages telling you which commands are unknown. Decide which of
the journal's specific commands or environments you used or
need. Write a little style file that defines them to do something
simple and sensible, or translates them into standard LATEX
commands. Or ask the journal to provide such a style file! If you are
a journal publisher, distribute your simplified style file to your
authors.
Why does TTH not recognize my ends of lines properly?
If you transfer a file from one operating system to another as a
binary file, the line-end codes are likely to be messed up. They use
different codes on Un*x, DOS, and Mac. Usually TEX is not bothered by
this. TTH is somewhat more sensitive. Use ASCII transfer.
TTH does not recognize evironment ... even though it
claims to.
Probably you left a spurious space, e.g. \begin {enumerate}
between the \begin and the following brace. TTH occasionally won't
accept that, even though LATEX does. It is bad style.
Why does TTH not recognize ... command from ... style
package?
Let's be perfectly clear here. TTH does not currently recognize
\usepackage and, with the exception of commands explicitly
mentioned in this manual, does not support any of the zillions
of extensions to LATEX that exist, even if they are part of the
``standard distribution''.
The file I ``published'' using Netscape Composer looks
messed up when viewed on a Mac.
Don't use Composer on TTH documents. See section 11.2.
In bordered tables I want an empty cell to look
empty. How do I make TTH do that?
HTML tables by default ``fill in'' an empty cell, so that it gives the
visual impression of being absent. This is sometimes useful, so TTH
does not prevent it. If you want it to look like an empty cell, put a
non-break space in it by &~& in the TEX.
Why does TTH mess up my \fbox, minipage, etc?
The whole concept of a ``box'' is not really translatable into
HTML. TTH tries to take reasonable action on encountering one. But in
some cases, especially in equations, it can't cope.
Why does TTH complain about my skip, space, ... command?
Dimensions are usually inappropriate for HTML. TTH
tries do something sensible with dimension, space, and glue
commands. Usually it is successful. If so, you need do nothing. In
some rare cases, you might see some irrelevant left-over characters
from the dimension command that have to be removed by hand.
How do I get caligraphic fonts, {\cal E}, AMS
fonts, etc?
You can't because browsers don't have access to them. TTH can only
support fonts that are available on the browsers that eventually visit
the page. By default TTH tells the browser to render caligraphic as
italic helvetica font. You may, if you wish, define \cal to be
something different, such as %%tth:\def\cal{\it\color{red}}.
Why does TTH turn double-quotes into an accent
instead of quotes?
In basic TEX the double quotes character
" is not defined, and hence may do anything that the local
installation feels like. Double quotes must be inserted by using two
quote '' or back-quote `` characters. In German TEX implementations,
the double-quotes character is used to provide the umlaut over accent
and for some other special needs. TTH supports these German uses in
some appropriate contexts. English speakers should adopt proper TEX
quote usage. There is essentially never a situation in LATEX where
it is advisable to use a double quote to represent itself outside of a
verbatim section (where it will naturally be treated literally). In
Plain TEX you might need it. If so, \char`" is an
absolutely fool-proof way to insert it. Here it is:".
You can also just enclose it in braces thus:{"}.
How do I include into a macro I am defining a # sign
for an HTML reference?
When you do \special{html:<a href="#reference">}
TTH just puts the html tag in the output verbatim. TEX does essentially the
same for its dvi file and the dvi processor later may or may not complain
about not understanding it; but generally it is ignored. However if you try
to define a macro like
\def\localhref{\special{html:<a href="#reference">}} then TEX
will complain as follows:
! Illegal parameter number in definition of \localref.
<to be read again>
r
l.3 \def\localref{\special{html:<a href="#r
eference">}}
? This problem is caused by TEX's syntax analysis of
the contents of the definition. One solution is to hide the
definition from TEX using %%tth:. An alternative definition
that avoids this problem must also be included for TEX's benefit, for
example thus:
\def\tthdump#1{#1}
\tthdump{\edef\localref{[a hyperreference]}}
%%tth:\def\localhref{\special{html:<a href="#reference">}}
Alternatively, use \# in place of # in the hypertex
reference. TTH specifically recognizes this as a literal and does
appropriate translation. For example
\def\localhref#1#2{\special{html:<a href="\##1">}#2\special{html:</a>}}
will use its first parameter as a local anchor reference, preceded by #,
and its second as the text of the anchor. The sequences \% and
\\ are also treated as escaped literals, inserting their second
character, inside a raw html section.
How do I construct a macro to take as a single
argument a URL, which may contain special TEX characters like
_ ~ @ &
etc, that makes TTH construct a hyperreference but TEX just enter it in the
text?
Use the built-in command \url{...}. This behaves in
essentially the same way as the command defined in LATEX's
url.sty. The reference will appear verbatim in the text (in teletype
font).
TTH seems not to work on WinNT when converting
included PostScript files, even though my ps2gif program works fine
from the command line. What is the problem?
The problem is not TTH. It appears to be an operating system
problem. The batch program ps2gif is breaking for some strange reason
when called from TTH. See footnote 6.
Why doesn't TTH automatically generate <head>
and <body> HTML tags?
First, the <head> and
<body> tags are optional in the HTML specification. There is
no need for TTH to generate them to statisfy the standard. Second, TEX
and LATEX files do not have a corresponding structural division into
separate head and body sections. It might seem as if LATEX does, with
\begin{document} being the divider, but there are many cases
where this mapping is incorrect. For example title may not be defined
until after \begin{document}, corresponding to the HTML body
section, whereas it must be in the head section. Finally, if TTH
automatically entered <head> and <body> tags, then the
thoughtful author would not be able to enter them where they ought to
be by using, for example:
%%tth: \begin{html} <head> \end{html}
Therefore, the choice not to produce these tags automatically
is a deliberate one based on a careful consideration of the advantages
and disadvantages. An author can always adjust their TEX code to
include them, if they wish to be pedantic about the division.
Why don't TEX commands get expanded in the HTML title?
In HTML, the stuff that goes in the <title>...</title> of a
page is not permitted by the specification to contain HTML tags -
things in angle brackets - and tags are not interpreted. If an
equation or some other command that TTH translates
into HTML formatting is in the title, then the title will break when
expanded. Therefore TTH never expands commands in the title, but
leaves them in the TEX form that they started as, since that is
about as easy to read as any unformatted mathematics.
Can TTH be made to support BibTEX bibliographies?
It already does; see 6.2. If TTH is not finding the .bbl file
even though you used the -L switch, then you probably forgot to
generate it using LATEX and BibTEX, or perhaps it is in the
wrong place.
1The problem with \rm in text is that HTML has no < rm > tag, and relies on cancelling all previous make (e.g.) < i > or < b > tags. TTHgold has a style switch -y that uses Cascading Style Sheets to solve this problem. However not all older browsers support CSS. The best solution is to avoid \rm by using proper grouping of non-roman text. (In equations \rm is essential, but TTH has a work-around in equations.)
2Conditionals \if and \ifx are not 100% TEX compatible for cases where they refer to internal TEX commands because TTH internals are not identical. Catcodes are also unknown to TTH.
3See appendix for TEX macros supporting these commands
4Using the ``span'' construct, and possibly cascading style sheets, it ought to be possible to insert tables in line. However NS4.7 and earlier do not behave rationally in this context. Let's hope this browser problem is soon fixed.
5The PNG graphics file format is an improved replacement for the GIF standard. Netscape has built in rendering for PNG. The GIF standard is plagued with legal problems related to a ridiculous patent on the type of file compression it uses.
6May 1999 reports indicate that there is a batch program in circulation bearing the comment ``:#batchified by cschenk@snafu.de'' that tries to implement the functionality of ps2gif and gives errors on WinNT when called by TTH but not when called from the command line. This problem appears to be related to memory management or other some operating system inadequacy. It would do everyone running on Wind*ws systems a favor if someone could figure out what the problem is and let me know at tth@hutchinson.belmont.ma.us. Meanwhile, it is reported that removing the pnmmargin command from the ps2gif batch file enables it to run. A Sep 99 report notes that on Win98 the pnmmargin command appears not to be available on the system. Remember, ps2gif is the user's responsibility.
7The alignment argument of the math array environment was ignored in TTH versions earlier than 2.20 but is now honored.
8See the file colordvi.tex for a list of the named colors.