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TITLE: Draft Amendment 2 to ISO/IEC 9541-1, Minor Enhancements to the Architecture to Address Font Technology Advances
SOURCE: Yushi Komachi
PROJECT: JTC1.18.27.1.2
PROJECT EDITOR: Yushi Komachi
STATUS: Draft text for ballot
ACTION: For information
DATE: 9 May 1997
DISTRIBUTION: WG8 and Liaisons
REFER TO:
REPLY TO: Dr. James David Mason
(ISO/IEC JTC1/SC18/WG8 Convenor)
Lockheed Martin Energy Systems
Information Management Services
1060 Commerce Park, M.S. 6480
Oak Ridge, TN 37831-6480 U.S.A.
Telephone: +1 423 574-6973
Facsimile: +1 423 574-0004
Network: masonjd@ornl.gov
http://www.ornl.gov/sgml/wg8/wg8home.htm
ftp://ftp.ornl.gov/pub/sgml/wg8/

Draft Amendment 2 to ISO/IEC 9541-1, Minor Enhancements to the Architecture to Address Font Technology Advances



1. Scope

This minor enhancement specifies additional properties of the Font Resource defined by ISO/IEC 9541-1. The properties make it possible to address advances in font technology and in the increasing complexity of document processing. The properties of this amendment are optional and in addition to those defined in ISO/IEC 9541-1:1991, with the interchange format being defined in Amendment 1 to ISO/IEC 9541-2:1991.

2. Normative references

The following standards contain provisions which, through reference in this text, constitute provisions of this amendment 2 to ISO/IEC 9541-1. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this amendment are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.

3. Definitions

For the purposes of this amendment, the following definitions apply.

3.1 body size:
The font size, measured along with the y axis of the glyph coodinate system.
3.2 extended body size:
A reference size with two components, measured respectively along the x and y axes of the glyph coordinate system.
3.3 design frame:
Dimensional expression that specifies the area inside which a set of glyph images (a subset of the set of glyph images) may be designed.
3.4 bounding box:
Dimensional expression to specify an actual area that a glyph image occupies within a design frame.
3.5 blackness:
The ratio of the blackened area of a glyph image to the extended body size area of the glyph image.

4. Notation

The extended Backus-Naur Form (BNF) specified in ISO/IEC 9541-1 and technical corrigendum 2 to it is used.

5. Properties

5.1 Vertical Unit and Horizontal Unit (VUNITS, HUNITS)

VUNITS and HUNITS are cardinals, the number of relative units equal to the extended body size of the font resource, as measured along the y axis and x axis respectively of the glyph coordinate system.

  verticalunit-property ::= verticalunit-name, verticalunit-value 
  verticalunit-name ::= STRUCTURED-NAME 
                      -- ISO/IEC 9541-1//VUNITS 
  verticalunit-value ::= CARDINAL 
  horizontalunit-property ::= horizontalunit-name,
                              horizontalunit-value
  horizontalunit-name ::= STRUCTURED-NAME 
                      -- ISO/IEC 9541-1//HUNITS 
  horizontalunit-value ::= CARDINAL 

NOTE 1 The ISO/IEC 9541-1 specifies body size by the property RELUNITS as measured only along the y axis of the glyph coordinate system. However, in some fonts, e.g., a certain Kanji font, dimensional references of their extended body size have to be defined in both x axis and y axis.

NOTE 2 The typical value of VUNITS should be 1000, so as to harmonize with that of RELUNITS.

5.2 Fill Ratio (FILLRATIO)

FILLRATIO is a property-list, specifying a blackness of a glyph image of a reference glyph in the font resource.

  fillratio-property ::= fillratio-name,  
                         fillratio-value-property-list  
  fillratio-name ::=STRUCTURED-NAME 
                 -- ISO/IEC 9541-1//FILLRATIO 
  fillratio-value-property-list ::= (blackness)+  
  blackness ::= reference-glyph, fillratio-value  
  reference-glyph ::= MESSAGE 
                 -- specification of a typical glyph
  fillratio-value ::= RATIONAL
                 -- (blackened area)x1000 /(VUNITS x HUNITS)  

NOTE 3 Fill Ratio is used to determine an appropriate font substitution.

NOTE 4 In Latin fonts, "I" or "i" is used as a reference glyph. In Japanese fonts, reference glyphs may be " •Ä" or "‚Ì".

5.3 Design Areas (DSNAREAS)

DSNAREAS is a property-list consisting of the property-lists that specify the design frames within which sets of glyph images are designed in their extended body sizes.

  designareas-property ::= designareas-name,
                          designareas-value-property-list 
  designareas-name ::=STRUCTURED-NAME 
                 -- ISO/IEC 9541-1//DSNAREAS
  designareas-value-property-list ::= (designarea-property |
                                       property-list)+
5.3.1 Design Area (DSNAREA)

DSNAREA is a property-list specifying the design frame as measured by rel-rationals along the y axis and x axis in each set of glyphs. The set of glyphs configures a subset of glyph collection of the font resource.

  designarea-property ::= designarea-name,
                          designarea-value-property-list
  designarea-name ::=STRUCTURED-NAME
                 -- ISO/IEC 9541-1//DSNAREA 
  designarea-value-property-list ::= (letter-face)+ 
  letter-face ::= glyphset-name, height, width
  glyphset-name ::= MESSAGE 
              -- specification of glyph-set name
  height ::= REL-RATIONAL 
              -- y value of the design frame
  width ::= REL-RATIONAL
              -- x value of the design frame

NOTE 5 A glyph-set need not be a registered glyph collection.

NOTE 6 The property DSNAREA shows an extent of glyph condense in a composed line or line progression.

5.4 Average ESC (AVRESC)

AVRESC is a property-list consisting of the property-lists that specify the average sizes of bounding boxes which the designed glyph shapes actually cover in their design area.

  averageesc-property ::= averageesc-name,
                          averageesc-value-property-list  
  averageesc-name ::=STRUCTURED-NAME  
                 -- ISO/IEC 9541-1//AVRESC
  averageesc-value-property-list ::= (averageesc-property | 
                                       property-list)+
5.4.1 Average LEN (AVRLEN)

AVRLEN is a property-list specifying the average sizes of bounding box as measured by rel-rationals along the y axis and x axis in each set of glyphs, e.g., a katakana glyph set. The set of glyphs configures a subset of glyph collection of the font resource.

  averagelen-property ::= averagelen-name,
                          averagelen-value-property-list
  averagelen-name ::=STRUCTURED-NAME
                 -- ISO/IEC 9541-1//DAVGELEN
  averagelen-value-property-list ::= (average-length)+  
  average-length ::= glyphset-name, height, width 
  glyphset-name ::= MESSAGE 
              -- specification of glyph-set name
  height ::= REL-RATIONAL 
              -- y value of the bounding box
  width ::= REL-RATIONAL
              -- x value of the bounding box

NOTE 7 A glyph-set need not be a registered glyph collection. An average escapement of a glyph collection can be specified by the property AVGESCY or AVGESCX. The property AVRLEN can specify an average escapement of apart of the glyph collection.

NOTE 8 The property AVRLEN shows a limit of glyph condense in a composed line or line progression. The simpler functions can be provided by a-zlength in Latin fonts.

NOTE 9 A relationship between VUNITS, HUNITS, DSNAREA and AVRLEN is shown in figure 5.1.

@@@@@@@@@@@@@@@@@@@@@@extended body 
@@@@@@@@@@@„¡„Ÿ„Ÿ„Ÿ„Ÿ„Ÿ„Ÿ„Ÿ„¢©@size (VUNITS x HUNITS)
@@@@@@@@@@@„ „¡„¦„Ÿ„Ÿ„Ÿ„¦„¢„ 
@@@@@@@@@@@„ „ „ @@@„ „ ©|@design frame (DSNAREA)
@@@@@@@@@@@„ „ „ @@@„ „ „ 
@@@@@@@@@@@„ „ „ @@@„ ©||@bounding box (AVRLEN) 
@@@@@@@@@@@„ „ „ @@@„ „ „ 
@@@@@@@@@@@„ „¤„¨„Ÿ„Ÿ„Ÿ„¨„£„ 
@@@@@@@@@@@„¤„Ÿ„Ÿ„Ÿ„Ÿ„Ÿ„Ÿ„Ÿ„£
@@@@Figure 5.1  The relationship between VUNITS, HUNITS, DSNAREA 
                    and AVRLEN. 
@@@@@NOTE 10 The figure 5.1 illustrates only the relative positions
                  of extended body size, design frame and bounding box.

5.5 Generalized Kendot (GENKENDOT)

In a simple formatting, kendots are supported by using the font property: Score with specifying KENDOT score object. However, the property SCORE can only describe a simple dot with its specified offset and thickness.

More complicated formatting may require a particular shape for kendot. Generalized Kendot includes the capability to specify dot shape.

  genkendot-property ::= genkendot-name, genkendot-value-property-list
  genkendot-name ::= STRUCTURED-NAME
                      -- ISO/IEC 9541-1//GENKENDOT
  genkendot-value-property-list ::= 
                      (genkendot-offsetx-property | 
                       genkendot-offsety-property | 
                       genkendot-thick-property | 
                       genkendot-shape-property)
  genkendot-offsetx-property ::= genkendot-offsetx-name,
                                 genkendot-offsetx-value
  genkendot-offsetx-name ::= STRUCTURED-NAME
                             -- ISO/IEC 9541-1//GENKENDOTOFFSETX
  genkendot-offsetx-value ::= REL-RATIONAL
  genkendot-offsety-property ::= genkendot-offsety-name,
                                 genkendot-offsety-value
  genkendot-offsety-name ::= STRUCTURED-NAME
                             -- ISO/IEC 9541-1//GENKENDOTOFFSETY
  genkendot-offsety-value ::= REL-RATIONAL
  genkendot-thick-property ::= genkendot-thick-name,
                               genkendot-thick-value
  genkendot-thick-name ::= STRUCTURED-NAME
                             -- ISO/IEC 9541-1//GENKENDOTTHICK
  genkendot-thick-value ::= REL-RATIONAL
  genekendot-shape-property ::= genkendot-shape-name, 
                                genkendot-shape-value 
  genkendot-shape-name ::= STRUCTURED-NAME
                             -- ISO/IEC 9541-1//GENKENDOTSHAPE
  genkendot-shape-value ::= STRUCTURED-NAME 
                             -- Dot Glyph Name