The content takes the form of a text file intended to be human- and computer-readable.
For example, glyphs in a BDF 2.2 font definition can specify rendering from top-to-bottom rather than simply left-to-right.
Note that although the bounding box is defined to be a 16 by 16 cell, this can be overridden for individual glyphs.
Although Adobe now refers to this file format as the Glyph BDF, they have retained the keyword CHARS in the final version of the specification.
Lines beginning with the word COMMENT can be inserted within a BDF file.
ENCODING 65 declares the decimal code point for this glyph in the font.
The scalable width is 1000 times the actual point size of the character—the same unit used in an Adobe Font Metric (AFM) file.
It is simply the offset on the X-axis to move the current point to the start of the next glyph.
In this example, the glyph is exactly 8 pixels wide, and so occupies exactly 8 bits (one byte) per line so that there is no padding.
The most significant bit of a line of raster data represents the leftmost pixel.
Version 2.2 of the BDF specification adds support for non-Western fonts.
Fonts can conceivably contain thousands of glyphs, some of which should be written left-to-right, some right-to-left, and some top-to-bottom.
In addition to keywords added for international support, version 2.2 adds the CONTENTVERSION declaration.
X Window font utilities support several properties that can be specified in the STARTPROPERTIES section of a BDF file.
X Window properties are specified using ISO 8859-1 encoding, which is an extension of ASCII.