symbols-a4

METAFONT can produce “proofs” of fonts—large, labeled versions that showcase the logical structure of
each character. In fact, proof mode is METAFONT’s default mode. To produce a proof of lightbulb10.mf,
issue the following commands at the operating-system prompt:
prompt> mf lightbulb10.mf ⇐ Produces lightbulb10.2602gf
prompt> gftodvi lightbulb10.2602gf ⇐ Produces lightbulb10.dvi
You can then view lightbulb10.dvi with any DVI viewer. The result is shown in Figure 4. Observe how the
grid defined with makegrid at the bottom of Figure 3 draws vertical lines at positions 0, sb, w/2, and w − sb
and horizontal lines at positions 0, −1pt, y2, and h. Similarly, observe how the penlabels command labels all
of the important coordinates: z1, z2, . . . , z8 and z67, which lightbulb.mf defines to lie between z6 and z7.
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8
7
1
3
67
Figure 4: Proof diagram of lightbulb10.mf
Most, if not all, TEX distributions include a Plain TEX file called testfont.tex which is useful for testing
new fonts in a variety of ways. One useful routine produces a table of all of the characters in the font:
prompt> tex testfont
This is TeX, Version 3.14159 (Web2C 7.3.1)
(/usr/share/texmf/tex/plain/base/testfont.tex
Name of the font to test = lightbulb10
Now type a test command (\help for help):)
*\table
*\bye
[1]
Output written on testfont.dvi (1 page, 1516 bytes).
Transcript written on testfont.log.
The resulting table, stored in testfont.dvi and illustrated in Figure 5, shows every character in the font.
To understand how to read the table, note that the character code for “A”—the only character defined by
lightbulb10.mf—is 41 in hexadecimal (base 16) and 101 in octal (base 8).
The LightBulb10 font is now usable by TEX. L ATEX 2ε, however, needs more information before documents
can use the font. First, we create a font-description file that tells L ATEX 2ε how to map fonts in a given font
family and encoding to a particular font in a particular font size. For symbol fonts, this mapping is fairly simple.
Symbol fonts almost always use the “U” (“Unknown”) font encoding and frequently occur in only one variant:
normal weight and non-italicized. The filename for a font-description file important; it must be of the form
“〈encoding〉〈family〉.fd”, where 〈encoding〉 is the lowercase version of the encoding name (typically “u” for
symbol fonts) and 〈family〉 is the name of the font family. For LightBulb10, let’s call this “bulb”. Figure 6 lists
the contents of ubulb.fd. The document “L ATEX 2ε Font Selection” [L AT00] describes \DeclareFontFamily
and \DeclareFontShape in detail, but the gist of ubulb.fd is first to declare a U-encoded version of the bulb
font family and then to specify that a L ATEX 2ε request for a U-encoded version of bulb with a (m)edium font
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