REVINPUT is the standard Toolbox data-entry routine.

               Arguments:

Max%        =  maximum number of characters which can
               be accepted.
Default$    =  default string which can be accepted by
               just pressing the <Enter> key.
Context%    =  set TRUE if context-sensitive help is
               available, in which case ... 
Topic$      =  name of the HELP Topic file to display
               whenever the <F1> key is pressed. 
ReturnCode% =  If entry is terminated by anything
               other than the <Enter> key, this
               variable will contain an explanatory
               return code ..
All the usual editing keys are supported and entry may
be terminated by either a carriage-return or <Escape>,
in which case any keyed-in characters will be ignored.

<L.Arrow>   =  Move cursor one character to the left
<R.Arrow>   =  Move cursor one character to the right
<Home>      =  Move cursor to first character of field
<End>       =  Move cursor to last character of field
<Ctrl End>  =  Clear from current cursor position to
               the end of the entry field.
<Insert>    =  Toggle between Insert and Overtype.
<Delete>    =  Delete character under the cursor.
<BackSpace> =  Replace character under cursor with a
               blank space and move the cursor one
               character to the left.
<F1>        =  pop up on-line HELP screen.

REVINPUT is also designed to be part of a  full-screen
data-entry system. Your program can examine the return
code  to determine whether the operator just wishes to 
terminate entry, or move forwards or backwards between
a number of entry fields.

Return Codes:   

1  =  <Escape>    abort entry returning a null string
2  =  <F2>        repeat previous entry for this field
3  =  <Up Arr>    pressed, move to previous field 
4  =  <Dn Arr>    pressed, move to next field
5  =  <Pg Up>     pressed, move to top of screen
6  =  <Pg Dn>     pressed, move to end of screen





 See also DATEINPUT for a keyboard routine specially
 designed to ask the operator for a date!!!!

