# Old BDF Spec 2.1

The historical BDF 2.1 specification for bitmap font headers, glyph metrics, character encoding, and bitmap data.

# Bitmap Distribution Format Version 2.1

**X Window System Standard**

**X Version 11, Release 6.7**

Copyright 1984, 1987, 1988 Adobe Systems, Inc.

Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appears in all copies and that both that copyright notice and this permission notice appear in supporting documentation.

The Bitmap Distribution Format (BDF), Version 2.1, is an X Consortium standard for font interchange, intended to be easily understood by both humans and computers.

## File Format

Character bitmap information will be distributed in a USASCII-encoded, human-readable form. Each file is encoded in the printable characters (octal 40 through 176) of USASCII plus carriage return and linefeed. Each file consists of a sequence of variable-length lines. Each line is terminated either by a carriage return (octal 015) and linefeed (octal 012) or by just a linefeed.

The information about a particular family and face at one size and orientation will be contained in one file. The file begins with information pertaining to the face as a whole, followed by the information and bitmaps for the individual characters.

## Font Bitmap Description File Format

A font bitmap description file has the following general form:

1. **STARTFONT** followed by a version number indicating the exact file format used. The version described here is 2.1.
2. Lines beginning with the word **COMMENT** may appear anywhere between the **STARTFONT** line and the **ENDFONT** line. These lines are ignored by font compilers.
3. **FONT** followed by either the XLFD font name (as specified in part III) or some private font name. Creators of private font name syntaxes are encouraged to register unique font name prefixes with the X Consortium to prevent naming conflicts. Note that the name continues all the way to the end of the line and may contain spaces.
4. **SIZE** followed by the point size of the characters, the x resolution, and the y resolution of the device for which these characters were intended.
5. **FONTBOUNDINGBOX** followed by the width in x, height in y, and the x and y displacement of the lower left corner from the origin.
6. Optionally, **STARTPROPERTIES** followed by the number of properties (**p**) that follow.
7. Then come **p** lines consisting of a word for the property name followed by either an integer or string surrounded by double-quotes (octal 042). Internal double-quote characters are indicated by using two in a row.

   Properties named **FONT_ASCENT**, **FONT_DESCENT**, and **DEFAULT_CHAR** should be provided to define the logical font-ascent, font-descent, and the default character for the font. These properties will be removed from the actual font properties in the binary form produced by a compiler. If these properties are not provided, a compiler may reject the font or compute (arbitrary) values for these properties.

8. The property section, if it exists, is terminated by **ENDPROPERTIES**.
9. **CHARS** followed by the number of character segments (**c**) that follow.
10. Then come **c** character segments of the form:

    - **STARTCHAR** followed by up to 14 characters (no blanks) of the descriptive name of the glyph.
    - **ENCODING** followed by one of the following forms:
      1. `<n>` − the glyph index, a positive integer representing the character code used to access the glyph in X requests, as defined by the encoded character set given by the **CHARSET_REGISTRY**-**CHARSET_ENCODING** font properties for XLFD conforming fonts.
      2. `-1 <n>` − equivalent to form above. This syntax is for backward compatibility with previous versions of this specification and is not recommended for new fonts.
      3. `-1` − an unencoded glyph. Some font compilers may discard unencoded glyphs, but in general, the glyph names may be used by font compilers and X servers to implement dynamic mapping of glyph repertoires to character encodings as seen through the X protocol.
    - **SWIDTH** followed by the scalable width in x and y of the character. Scalable widths are in units of 1/1000th of the size of the character. If the size of the character is p points, the width information must be scaled by p/1000 to get the width of the character in printer’s points. This width information should be considered as a vector indicating the position of the next character’s origin relative to the origin of this character.
    - **DWIDTH** followed by the width in x and y of the character in device units. Like the **SWIDTH**, this width information is a vector indicating the position of the next character’s origin relative to the origin of this character.
    - **BBX** followed by the width in x (BBw), height in y (BBh), and x and y displacement (BBox, BBoy) of the lower left corner from the origin of the character.
    - The optional word **ATTRIBUTES** followed by the attributes as 4 hex-encoded characters. The interpretation of these attributes is undefined in this document.
    - **BITMAP** followed by h lines of hex-encoded bitmap, padded on the right with zeros to the nearest byte (that is, multiple of 8).
    - **ENDCHAR**.

11. The file is terminated with the word **ENDFONT**.

## Metric Information

Figures 1 and 2 best illustrate the bitmap format and character metric information.

_(The image is missing in the original official PDF file)_

BBw = 9, BBh = 22, BBox = -2, BBoy = -6  
DWIDTH = 8 0  
SWIDTH = 355 0  
" + " = character origin and width

**Figure 1: An example of a descender**

_(The image is missing in the original official PDF file)_

BBh = 6, BBw = 4, BBox = +2, BBoy = +12  
DWIDTH = 5 0  
SWIDTH = 223 0  
" + " = character origin and width

**Figure 2: An example with the origin outside the bounding box**

## An Example File

The following is an abbreviated example of a bitmap file containing the specification of two characters (the _j_ and _quoteright_ in figures 1 and 2).

```
STARTFONT 2.1
COMMENT This is a sample font in 2.1 format.
FONT -Adobe-Helvetica-Bold-R-Normal--24-240-75-75-P-65-ISO8859-1
SIZE 24 75 75
FONTBOUNDINGBOX924 -2 -6
STARTPROPERTIES 19
FOUNDRY "Adobe"
FAMILY "Helvetica"
WEIGHT_NAME "Bold"
SLANT "R"
SETWIDTH_NAME "Normal"
ADD_STYLE_NAME ""
PIXEL_SIZE 24
POINT_SIZE 240
RESOLUTION_X 75
RESOLUTION_Y 75
SPACING "P"
AVERAGE_WIDTH 65
CHARSET_REGISTRY "ISO8859"
CHARSET_ENCODING "1"
MIN_SPACE 4
FONT_ASCENT 21
FONT_DESCENT 7
COPYRIGHT "Copyright (c) 1987 Adobe Systems, Inc."
NOTICE "Helvetica is a registered trademark of Linotype Inc."
ENDPROPERTIES
CHARS 2
STARTCHAR j
ENCODING 106
SWIDTH 355 0
DWIDTH 8 0
BBX 9 22 -2 -6
BITMAP
0380
0380
0380
0380
0000
0700
0700
0700
0700
0E00
0E00
0E00
0E00
0E00
1C00
1C00
1C00
1C00
3C00
7800
F000
E000
ENDCHAR
STARTCHAR quoteright
ENCODING 39
SWIDTH 223 0
DWIDTH 5 0
BBX 4 6 2 12
ATTRIBUTES 01C0
BITMAP
70
70
70
60
E0
C0
ENDCHAR
ENDFONT
```