InfoMagic Standards 1994 January/InfoMagic Standards - January 1994.iso/ccitt/1992/t/t411_1.asc

Text File | 1991-12-31 | 44KB | 1,088 lines

Recommendation T.411




               OPEN DOCUMENT ARCHITECTURE (ODA) AND INTERCHANGE FORMAT

                         INTRODUCTION AND GENERAL PRINCIPLES



                                      CONTENTS


       Introduction

1      Scope
2      Normative reference
3      Definitions
4      Conventions
       4.1  Names of attributes
       4.2  Names of attribute values
       4.3  Component and component description
       4.4  Introduction of terms

5      General concept of ODA

       5.1  Purpose of ODA
       5.2  Overall concept of ODA
       5.3  Document processing model

6      Overview of the Recommendations in the T.410 series

       6.1  T.411 Introduction and general principles
       6.2  T.412 Document structures
       6.3  T.414 Document profile
       6.4  T.415 Open document interchange format (ODIF)
       6.5  T.416 Character content architectures
       6.6  T.417 Raster graphics content architectures
       6.7  T.418 Geometric graphics content architectures

7      Inter-dependencies of the Recommendations
8      Conformance
9      Document application profile
       9.1  General principles for defining a document application profile
       9.2  Rules for defining a document application profile

Annex A - References to other Recommendations, standards and registers
Annex B - Relationships with other Recommendations and standards
Annex C - Correspondence between Recommendation T.73 (1984) and Recommendations in the T.410 series

       C.1  Data stream format
       C.2  Presentation capabilities descriptor
       C.3  Attributes

Annex D - Principles for the assignment of ASN.1 object identifier values
Annex E - Use of MHS to interchange documents conforming to the T.410 series of Recommendations




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       Introduction

       Recommendation T.411 is one of the T.410 series of Recommendations which has been prepared by CCITT COM
VIII/WP 2 for the interchange of documents in the context of document architecture transfer, and manipulation.

       This series of Recommendations specifies a document architecture (known as the "Open Document Architecture"
ODA) and an interchange format (known as the "Open document interchange format" ODIF).

       The T.410 series of Recommendations consists of:

       -    Rec. T.411: Open document architecture (ODA) and interchange format - Introduction and general

            principles;

       -    Rec. T.412: Document structures;

       -    Rec. T.414: Document profile;

       -    Rec. T.415: Open document interchange format (ODIF);

       -    Rec. T.416: Character content architectures;

       -    Rec. T.417: Raster graphics content architectures;

       -    Rec. T.418: Geometric graphics content architectures.

       Note - At present, there is no Recommendation T.413

       Other Recommendations may be added to this series.

       The T.410 series of Recommendations supersedes Recommendation T.73 (1984)

       Development of the T.410 series has been in parallel with:

       -    ECMA-101: "Office document architecture";

       -    ISO 8613: "Information processing - Text and office systems - Office document architecture (ODA) and
            interchange format".


1      Scope


1.1    The purpose of the T.410 series of Recommendations is to facilitate the interchange of documents.

       In the context of the T.410 series, documents are considered to be items such as memoranda, letters, invoices,
forms and reports, which may include pictures and tabular material. The content elements used within the documents may
include graphic characters, geometric graphics elements and raster graphics elements, all potentially within one document.

       Note - The T.410 series is designed to allow for extensions, including typographical features, colour, spreadsheets
and additional types of content such as sound.

1.2    The T.410 series applies to the interchange of documents by means of data communications.

       The T.410 series provides for the interchange of documents for either or both of the following purposes:
       -    to allow presentation as intended by the originator;
       -    to allow processing such as editing and reformatting.
       The composition of a document in interchange can take several forms:
       -    formatted form, allowing presentation of the document;





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       -    processable form, allowing processing of the document;
       -    formatted processable form, allowing both presentation and processing.
       The T.410 series also provides for the interchange of ODA information structures used for the processing of
interchanged documents.
       Furthermore, the T.410 series allows for the interchange of documents containing one or more different types of
content, such as character text, images, graphics and sound.

1.3    This Recommendation:

       -    introduces the T.410 series as a whole;
       -    gives the references necessary for all the Recommendations pertaining to this series;
       -    defines terms used in the context of the T.410 series;
       -    presents the concepts of the document architecture;
       -    gives an overview of all the Recommendations in the T.410 series;
       -    describes the inter-dependencies of these Recommendations;
       -    defines conformance to the T.410 series;
       -    gives rules for defining document application profiles.
       Annex A lists other Recommendations, standards and registers to which references are made, but that are not
indispensable for the application of the T.410 series.
       Annex B describes the relationships of the T.410 series with other Recommendations and standards.
       Annex C describes the correspondence between Recommendation T.73 and the T.410 series of Recommendations.
       Annex D establishes the Principles for the assignment of ASN.1 object identifier values in the T.410 series of
Recommendations.
       Annex E defines the use of MHS to interchange documents conforming to the T.410 series of Recommendations.


2      Normative references


       The following Recommendations and International Standards contain provisions which, through reference in this
text, constitute provisions of the T.410 series of Recommendations. At the time of publication, the editions indicated were
valid. All standards are subject to revision, and parties to agreements based on this Recommendation are encouraged to
investigate the possibility of applying the most recent edition of the Recommendations and standards listed below. Members
of IEC and ISO maintain registers of currently valid International Standards.
       The following references are applicable to the whole of the T.410 series of Recommendations.
       -    Rec. T.4 (1984): Standardization of group 3 facsimile apparatus for document transmission
       -    Rec. T.6 (1984): Facsimile coding schemes and coding control functions for group 4 facsimile apparatus
       -    Rec. T.50 (1984): International alphabet No. 5
       -    Rec. T.60 (1984): Terminal equipment for use in the teletex service
       -    Rec. T.101 (1984): International interworking for videotex services
       -    Rec. X.208 (1988): Specification of abstract syntax notation one (ASN.1)
       -    Rec. X.209 (1988): Specification of basic encoding rules for abstract syntax notation one (ASN.1)
       -    Rec. T.412 (1988): Open document architecture (ODA) and interchange format - Document structures









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       -    Rec. T.414 (1988): Open document architecture (ODA) and interchange format - Document profile

       -    Rec. T.415 (1988): Open document architecture (ODA) and interchange format - Open document

            interchange format (ODIF)

       -    Rec. T.416 (1988): Open document architecture (ODA) and interchange format - Character content

            architectures

       -    Rec. T.417 (1988): Open document architecture (ODA) and interchange format - Raster graphics content

            architectures

       -    Rec. T.418 (1988): Open document architecture (ODA) and interchange format - Geometric graphics content

            architectures

       -    ISO 2022 (1986): Information processing - ISO 7-bit and 8-bit coded character sets - Code extension

            techniques

       -    ISO 6429 (1983): Information Processing - ISO 7-bit and 8-bit coded character sets - Additional control

            functions for character-imaging devices1)

       -    ISO 6937-1 (1983): Information processing - Coded character sets for text communication - Part 1: General

            introduction

       -    ISO 6937-2 (1983): Information Processing - Coded character sets for text communication - Part 2: Latin

            alphabetic and non-alphabetic graphic characters

       -    ISO 6937-3 (1983): Information processing - Coded character sets for text communication - Part 3: Control
            functions for page-image format1)
       -    ISO 8601: Data elements and interchange format - Information interchange - Representation of dates and
            times2)
       -    ISO 8632-1 (1987): Information processing systems - Computer graphics - Metafile for the storage and
            transfer of picture description information (CGM) - Part 1: Functional specification
       -    ISO 8632-3 (1987): Information processing systems - Computer graphics - Metafile for the storage and
            transfer of picture description information (CGM) - Part 3: Binary encoding
       -    ISO 9541-1: Information processing - Font and character information interchange - Part 1:  introduction (2)
       -    ISO 9541-2: Information processing - Font and character information interchange - Part 2:  Registration and
            naming procedures2)
       -    ISO 9541-5: Information processing - Font and character information interchange - Part 5:  Font attributes
            and character model2)

       -    ISO 9541-6: Information processing - Font and character information interchange - Part 6:  Font and
            character attribute subsets and applications2)


3      Definitions


       For the purposes of the T.410 series of Recommendations, the following definitions apply:

3.1    active position



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       The point at which the action specified by the next character is to be effected.


────────
  1)   Under revision.
  2)   To be published.



























































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3.2    aligned around
       A tabulation alignment that positions the sequence of character images for a specified character string such that
the position point of the character image of the first instance of a specified group of characters within that string is positioned
at the tabulation stop.
3.3    aspect ratio
       The ratio of the dimension of a pel array in the direction of the pel path to the dimension on the direction of the
line progression.
3.4    assured reproduction area
       The rectangular area that remains on the nominal page after deducting an agreed allowance for edge losses.
3.5    attribute
       An element of a constituent of a document that has a name and a value and that expresses a characteristic of this
constituent or a relationship with one or more constituents.
3.6    available area
       The area determined by the document layout process into which the content portion is formatted by the content
layout process.
3.7    basic component
       A basic logical or layout object, or an object class from which basic logical or layout objects may be derived.
3.8    basic layout object
       An object in the specific layout structure that has no subordinate.
3.9    basic logical object
       An object in the specific logical structure that has no subordinate.
3.10   basic measurement unit (BMU)
       A unit of linear measurement equal to 1/1200 of 25.4 mm.
       Note - A locally defined scaling factor may be used to map the document to a particular imaging device.
3.11   basic value
       An attribute value, a control function parameter value or the value of any other capability that is unconditionally
allowed in document interchange in the context of a given document application profile.
3.12   binding
       A pair comprising an identifier and a value, where the value may be of any type, may be specified by an
expression, and is accessed through use of the binding identifier.
3.13   block
       A type of basic layout component that corresponds to a rectangular area within a frame or a page.
3.14   bottom edge
       The edge of the positioning area of a basic layout object that is in the direction of the line progression.
3.15   bottom left corner
       The corner of a layout object that is least progressed in the horizontal direction and most progressed in the vertical
direction of this layout object.
3.16   bottom right corner
       The corner of a layout object that is most progressed both in the horizontal and vertical directions of this layout
object.









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3.17   centred
       1)   The result of a layout or imaging process that positions the sequence of character images for a line such
            that the distance from the line home position to the position point of the first character image is
            approximately equal to the distance from the escapement point of the last character image to the end edge
            of the positioning area.
       2)   A tabulation alignment that positions the sequence of character images for a specified character string such
            that the distance from the position point of the first character image to the tabulation stop is approximately
            equal to the distance from the tabulation stop to the escapement point of the last character image.
       Note - The term "centred" is also used in the parameter "alignment" of the attribute "position" and in the attribute
"block alignment".
3.18   character
       A member of a set of elements used for the organization, control and representation of information.
3.19   character base line
       A line across a character image, in the horizontal direction when the character image is in its intended viewing
orientation.
3.20   character image
       The human perceptible rendering of a character on a presentation medium.
3.21   character orientation
       The direction of the character base line relative to the character path.
3.22   character path
       The direction of progression of successive character images within a line box.
3.23   character sequence
       A sequence of characters intended to be presented as one or more lines.
3.24   characters spacing (for constant spacing fonts only)
       The distance between the position points of successive character images when the inter- character space equals
zero.
3.25   clipped array
       The actual pel array to be imaged as determined by taking account of all clipping parameters.
3.26   complete generator set
       A constituent of a document consisting of a document root object class description and at least one level of
subordinate object class descriptions which are used to control the creation and/or modification of the set of object
descriptions representing a corresponding specific structure.
3.27   component
       An object or an object class.
3.28   composite component
       A composite logical or layout object, or an object class from which composite logical or layout objects may be
derived.
3.29   composite layout object
       An object in the layout structure that has one or more subordinate objects.
3.30   composite logical object
       An object in the logical structure that has one or more subordinate objects.
3.31   constant spacing
       The characteristic of a font wherein the distance between the position point and the escapement point is the same
for all character images.





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3.32   constituent
       A set of attributes that is one of the following types: a document profile, an object description, an object class
description, a presentation style, a layout style or a content portion description.
3.33   content
       The information conveyed by the document, other than the structural information, and that is intended for human
perception.
3.34   content architecture
       Rules for defining the internal structure and representation of the content of basic components in terms of a set of
content elements, attributes and control functions, and guidelines for the presentation of the content.
3.35   content architecture class
       The rules for defining the internal structure and representation of the content of basic components in one of a set
of forms defined for each type of content element.
       Note - Examples of content architecture classes are formatted form, processable form and formatted processable
form in the case of character content elements.
3.36   content architecture level
       An identified subset of the features pertaining to a content architecture class.
3.37   content editing process
       The process that creates new content or modifies previous content.
3.38   content element
       A basic element of the content of a document.
3.39   content layout process
       The process that, interacting with the document layout process, consists of the formatting of content portions into
available areas and the determination of the sizes of blocks in accordance with information contained in the presentation
styles.
3.40   content portion
       The result of partitioning the content of a document according to its logical and/or layout structure.
3.41   content portion description
       A constituent of a document, representing a content portion that consists of content information and attributes to
specify the properties of its content information.
3.42   content type
       A category of content elements such as graphic characters, raster graphic elements and geometric graphic
elements.
3.43   control function
       An element of a character set that affects the recording, processing, transmission or interpretation of data, and that
has a coded representation consisting of one or more bit combinations.
       Note - Examples of control functions are Select Graphic Rendition (SGR) in character content architectures and Set
Line Type in geometric graphics content architectures.
3.44   current layout position
       The identification of a lowest level frame which is maintained during the layout process for each layout stream
which occurs.
3.45   data structure
       A set of data items and the relationship among them representing the whole or a part of a constituent.








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       Note - The data items constituting a data structure represent attributes of the document, the document profile, the
component, the style or the content portion concerned.

3.46   description

       A constituent that corresponds to a structural element.

3.47   descriptor

       A data structure representing the document profile, an object class description, a layout style, a presentation style
or an object description.

3.48   document

       A structured amount of information intended for human perception, that can be interchanged as a unit between
users and/or systems.

3.49   document application profile

       The specification of a combination of features defined in the T.410 series, intended to form a subset to fulfil the
requirements of an application.
3.50   document architecture
       1)   Rules for defining the structure of documents, in terms of a set of components and content portions, and
            the representation of documents in terms of constituents and attributes.
       2)   The structural information of a document consisting of the set of one or more of the following structures:
            specific logical structure, specific layout structure, generic logical structure and/or generic layout structure.
3.51   document architecture class
       The rules for defining the structure and representation of documents in formatted form, processable form or
formatted processable form.
3.52   document architecture level
       An identified subset of the features pertaining to a document architecture class.
3.53   document body
       The part of a document that may include a generic logical and layout structure, specific logical and layout structure,
layout and presentation styles but excludes the document profile.
3.54   document class
       A set of logical object class descriptions, layout object class descriptions, generic content portion descriptions,
styles and a document profile, that specifies a set of documents with common characteristics.
3.55   document class description
       The specification of a document class.
3.56   document layout process
       The process that creates a specific layout structure in accordance with the generic layout structure and information
contained in the specific logical structure, the generic logical structure and the layout styles.
3.57   document layout root
       The composite object of the specific layout structure at the highest level of the hierarchy.
3.58   document logical root
       The composite object of the specific logical structure at the highest level of the hierarchy.
3.59   document profile
       A set of attributes which specifies the characteristics of the document as a whole.








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3.60   document profile level
       An identified subset of the features pertaining to the document profile.
3.61   editing process
       The stage of a document processing that consists of the content editing process and the logical structure editing
process.
3.62   end-aligned
       1)   The result of a layout or imaging process that positions the sequence of character images for a line such
            that the escapement point of the last character image is positioned at the end edge of the positioning area.
       2)   A tabulation alignment that positions the sequence of character images for a specified character string such
            that the escapement point of the last character image is positioned at the tabulation stop.
3.63   end edge
       The edge of the positioning area of a basic layout object that is in the direction of the character path.
3.64   escapement point
       A reference point associated with a character image that is used for positioning of the next character image.
3.65   external document class
       A document class referred to by the document profile of an interchanged document containing no generic structure.
3.66   factor set
       One or more object class descriptions which are used to factorise the attributes of object descriptions representing
a specific structure.
3.67   filing
       The storage of a document according to some defined method in order to facilitate retrieval of the document.
3.68   font
       A set of character images normally with a common design and size.
3.69   font size
       The height of the character images in a font.
3.70   formatted form
       A form of representation of a document that allows the presentation of the document as intended by the originator
and that does not support editing and (re)formatting.
3.71   formatted processable form
       A form of representation of the document that allows presentation of the document as intended by the originator
and also supports editing and (re)formatting.
3.72   formatting
       The carrying out of operations to determine the layout of a document.
3.73   frame
       A type of composite layout component that corresponds to a rectangular area within a page or another frame.
3.74   generic content portion
       A content portion associated with an object class.
3.75   generic content portion description
       A content portion description associated with an object class description.










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3.76   generic-document
       A structured amount of information intended for the interchange of generic structures, and optionally associated
styles and content portions, for use in the processing of interchanged documents.
3.77   generic layout structure
       A set of layout object classes and associated generic content portions.
3.78   geometric logical structure
       A set of logical object classes and associated generic content portions.
3.79   geometric graphic element
       A graphic element used to describe an image by geometric graphical means.
       Note - Geometric graphic elements include those describing primitive geometric shapes such as points, arcs, lines.
3.80   graphic character
       A member of a set of graphic symbols used for the representation of information.
       Note - Graphic characters include simple alphanumeric characters (for example, accented letters) and pictorial
characters (for example, mosaics).
3.81   graphic element
       A content element that is capable of having a visual representation.
       Note - Three types of graphic elements are distinguished in the T.410 series of Recommendations:  graphic
characters, geometric graphics elements and raster graphics elements.
3.82   hard line terminator
       A line terminator that is intended not to be removed in a re-formatting process.
3.83   horizontal direction (of a layout object)
       The direction in a layout object relative to which content architectures may define attributes determined using the
horizontal axis of the page.
3.84   imaging order
       The order of precedence of layout objects for imaging in the layout object to which they are immediately
subordinate.
3.85   imaging process
       The process of producing a document on a presentation medium in human perceptible form, making use of the
document profile, specific and generic layout structures, presentation styles and content portions.
3.86   indentation
       The result of a layout or imaging process that causes the sequence of character images for a line to begin at a
distance from the line home position in the direction of the character path.
3.87   initial point
       1)   The point associated with a basic layout object relative to which all line boxes imaged within that basic
            layout object are positioned (character content architectures Recommendation T.416).
       2)   The point associated with a basic layout object relative to which all pels imaged within that basic layout
            object are positioned (raster graphics content architectures Recommendation T.417).
3.88   interchange
       The process of transferring a document from an originating system to a receiving system.
3.89   interchange data element
       A data structure representing a constituent of a document.









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3.90   interchange format

       The rules for representing a document for the purpose of interchange.

3.91   interchange format class

       A form of interchange format suitable to a specific application.

       Note - In the T.410 series of Recommendations, the defined classes differ by the ordering of the interchange data

elements or by the coding.

3.92   inter-character space

       An additional amount of spacing that is included between adjacent character images.

3.93   intersection

       The common area of two or more layout objects that overlap each other partially or fully on the presentation

medium.

3.94   item identifier

       A string of characters preceding the first line of characters in a content portion that is used to identify the

subsequent text.

3.95   justified

       The result of a layout or imaging process that varies the width of the space character and/or the inter-character
space to produce a simultaneously start═aligned and end-aligned presentation of the text.
3.96   kern
       The part of a character which extends beyond its position point or escapement point.
3.97   layout category
       The association of basic logical objects with lowest level frames such that the content of these basic logical objects
is placed in the appropriate frames.
3.98   layout object
       An element of the specific layout structure of a document, for example, page, block.
3.99   layout object class
       An element of the generic layout structure from which a set of layout objects with common characteristics may be
derived, for example, pages with common headers and footers.
3.100  layout process
       The stage of a document processing that consists of the document layout process and the content layout process.
       Note - This is also referred to as formatting.
3.101  layout stream
       A set of basic logical objects pertaining to the same layout category.
3.102  layout structure
       1)   The result of dividing and subdividing the content of a document into increasingly smaller parts, on the
            basis of the presentation, for example, into pages, blocks.
       2)   All layout objects and associated content portions forming the layout hierarchy of a document.
3.103  layout style
       A constituent of the document, referred to/from a logical component, that guides the creation of a specific layout



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structure.

































































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3.104  leading edge

       The edge of a frame or block that is orthogonal to the direction of the layout path and that is met first, from the
outside of the frame or the block, in the opposite direction of the layout path.
3.105  left hand edge

       The edge of a frame or block that is parallel to the direction of the layout path and that is met first, from the
outside of the frame or the block, in the direction at an angle of 270o counterclockwise relative to the direction of the layout
path.
3.106  line box

       A rectangular area within which a sequence of character images are positioned.

3.107  line home position

       The point within a line box that is used for positioning that line box.

3.108  line progression

       1)   The direction of progression of successive line boxes within a basic layout object (character content

            architectures Recommendation T.416).

       2)   the direction of progression of successive lines of pels within a basic layout object (raster graphics content

            architectures Recommendation T.417).

3.109  lines spacing

       1)   The distance between two adjacent reference lines within a basic layout object (character content

            architectures Recommendation T.416).

       2)   The distance between two adjacent lines of pels within a basic layout object (raster graphics content

            architectures Recommendation T.417).

3.110  line terminator

       A control function or combination of control functions that indicates the end of a line or the end of a character
sequence.
3.111  logical object
       An element of the generic logical structure of a document which may have a meaning that is significant to the
application or user, for example, chapter, section, paragraph.
3.112  logical object class
       An element of the generic logical structure from which a set of logical objects with common characteristics may be
derived, for example, composite logical objects representing sections with a common internal structure.
3.113  logical structure
       1)   The result of dividing and subdividing the content of a document into increasingly smaller parts, on the
            basis of the human-perceptible meaning of the content, for example, into chapters, sections, paragraphs.
       2)   All logical objects and associated content portions representing the logical hierarchy of a document.
3.114  logical structure editing process
       The process that creates a new specific logical structure or modifies a previous specific logical structure and
allocates or re-allocates content to basic logical objects.
3.115  mandatory attribute
       An attribute which, when applicable to a constituent, must be specified explicitly in that constituent.




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3.116  nominal page

       A rectangular area which, as assumed by the sender of a document, has the ideal size of the presentation surface.

       Note - Examples of ideal sizes are given in ISO 216.

3.117  non-basic

       A qualifier for attribute values, control function parameter values and other capabilities that are only allowed in
document interchange in the context of a given document application profile if their use is declared in the document profile.
3.118  non-mandatory attribute

       An attribute which, when applicable to a constituent, need not be specified explicitly; if the attribute is not specified

explicitly in a given constituent, the attribute does not apply.

3.119  object

       An element of the specific layout structure or of the specific logical structure.

3.120  object class

       An element of a generic structure from which objects with common characteristics may be derived.

3.121  object class description

       A set of attributes that specify the properties of an object class including its relationships, if any, with other
components.
3.122  object description
       A set of attributes that specify the properties of an object including its relationships, if any, with other components.
3.123  object type
       A property of every component that specifies which attributes are permitted in the description to which it applies
and indicates the role of the component in the document architecture.
3.124  orphan
       One or more lines of text that is associated with subsequent text but isolated from it by a page or column
boundary.
3.125  overhang
       The result of a layout or imaging process that positions the sequence of character images for a line to begin at a
distance from the line home position in the direction opposite to the character path.
3.126  page
       A layout component that corresponds to a rectangular area used for presenting the content of the document.
3.127  page coordinate system
       An orthogonal co-ordinate system whose origin is the top left corner of the page; its horizontal axis and its vertical
axis coincide with the top edge and the left edge of the page, respectively.
3.128  page set
       A composite layout component that represents a collection of pages or further page sets.
3.129  pairwise kerning
       The distance between two adjacent character images depending on the combination of the two characters together
rather than separately.








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3.130  parallel annotation

       Two sequential character strings that are presented in parallel, wherein the second string is used to indicate the

pronunciation or interpretation of the first string.

3.131  partial generator set

       A collection consisting of hierarchically related object class descriptions which are used to guide the creation of
hierarchically related corresponding object descriptions but does not fully specify all specific structures that may be created.
3.132  pel array

       A two-dimensional array of pels used to represent a pictorial image.

3.133  pel path

       The direction of progression of successive pels along a line within a basic layout object.

3.134  pel spacing

       The distance between any two successive pels along a line within a basic layout object.

3.135  picture element (pel)

       The smallest graphic element that can be independently addressed within a picture; (an alternative term for raster
graphics element).
3.136  positioning area
       The rectangular area within a basic layout object within which the position points and the escapement points of all
character images are located.
3.137  position point
       The point relative to which the character image is placed i.e. the character is imaged with the position point at the
active position.
3.138  presentation
       The operation of rendering a document in a form perceptible to a human being.
3.139  presentation medium
       The carrier of information in a form perceptible to a human being.
3.140  presentation style
       A constituent of the document, referred to from a basic logical or layout component, which guides the format and
appearance of the document content.
3.141  presentation surface
       A two-dimensional presentation medium (such as paper, film, video display screen) on which the formatted form of
a document may be displayed for human viewing.
3.142  processable form
       A form of representation of a document that allows editing and formatting.
3.143  processing
       The carrying out of operations on a document, including editing, reformatting, presentation, filing and retrieval.
3.144  raster graphics element
       An alternative term for a picture element (pel).
3.145  reformatting
       The carrying out of operations to determine the new layout of a previously formatted document.



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3.146  reference area

       A rectangular area within a basic layout object, with its side equal to the pel spacing and the line spacing, within

which the main part of a pel is imaged.

3.147  reference line

       A line through the line home position and parallel to the character path.

3.148  reference point

       The point at the corner of the reference area situated in the opposite direction of both pel path and line

progression and which is used for positioning a pel.

3.149  region of interest

       A rectangular area within a virtual device coordinate space, with sides which are parallel to the axes of its
coordinate system, surrounding those (parts of)  geometric graphics elements that are intended to be imaged.
3.150  resource document

       A generic-document containing one or more object class descriptions referred to by one or more object class

descriptions of another document.

3.151  retrieval

       The recovery of previously filed information.

3.152  right hand edge

       The edge of a frame or block that is parallel to the direction of the layout path and that is met first, from the
outside of the frame or the block, in the direction at an angle of 90o counterclockwise relative to the direction of the layout
path.
3.153  scaled measurement unit (SMU)
       A unit of linear measurement used for positioning and dimensioning layout objects and content elements on a
presentation surface, its value being equal to the basic measurement unit (BMU) times the unit scaling.
3.154  sequential layout order
       The sequential order in which layout objects are to be imaged when an imaging order is not specified.
3.155  sequential logical order
       The sequential order in which logical objects are to be processed by the layout process.
3.156  sequential order
       A convention for ordering the objects in a structure such that each object is succeeded by all of its immediate
subordinates, before any other object with the same immediate superior, i.e. in order tree traversal.
3.157  soft line terminator
       A line terminator that is allowed to be removed, relocated or replaced in a subsequent layout process.
3.158  spacing ratio
       The ratio of line spacing to pel spacing.
3.159  specific layout structure
       A set of layout objects and associated content portions.
3.160  specific logical structure
       A set of logical objects and associated content portions.






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3.161  start-aligned

       1)   The result of a layout or imaging process that positions the sequence of character images for a line such
            that the position point of the first character image of that sequence is positioned on the line home position
            or at the point specified by the first line indentation or overhang if any.
       2)   A tabulation alignment that positions the sequence of character images for a specified character string such
            that the position point of the first character image of that sequence is positioned at the tabulation stop.
3.162  start edge

       The edge of the positioning area of a basic layout object that is in the direction opposite to the character path.

3.163  structural element

       The structural elements of a document are the content portion, the object and the object class.

3.164  tabulation alignment

       A layout or imaging process that causes the sequence of character images for a specified character string to be
positioned according to a specified method, (start-aligned, end-aligned, centred or aligned-around) at a specified point
(tabulation stop) along a reference line.

3.165  tabulation stop

       A position along a reference line that is to be used for a specified method (start-aligned, end-aligned, centred or

aligned-around) of tabulation alignment.

3.166  text unit

       A data structure representing a content portion description.

3.167  top edge

       The edge of the positioning area of a basic layout object that is in the direction opposite to the line progression.
3.168  top left corner
       The corner of a layout object that is least progressed both in the horizontal and vertical directions of this layout
object.
3.169  top right corner
       The corner of a layout object that is most progressed in the horizontal direction and least progressed in the vertical
direction of this layout object.
3.170  trailing edge
       The edge of a frame or block that is orthogonal to the direction of the layout path and that is met first, from the
outside of the frame or the block, in the direction of the layout path.
3.171  unit scaling
       A scaling factor (an integer or a fraction) that is applied to the basic measurement unit (BMU) to derive a scaled
measurement unit (SMU).
3.172  variable spacing
       The characteristic of a font wherein the distance between the position point and the escapement point for different
character images may be different.
3.173  widow
       One or more lines of text associated with preceding text but isolated from it by a page or column boundary.






                                                    Fascicle VII.6 - Rec. T.411      18