Chapter 6: Specials
As not every publishing feature is built-in to TeX, the creator of
TeX, Donald E. Knuth, made sure that a facility to insert ``hooks''
into a dvi file was available. These hooks are called specials
and are invoked via the \special command. For example, if you put the
command \special{Hello} in a TeX file, the resulting dvi file
will contain a \special opcode with argument Hello. TeX
postprocessors (such as dvi viewers or printer drivers) can then
interpret the \special's and take the appropriate action.
One of the more common uses of the \special is to insert figure files
into a TeX document. For example, the LATEX graphics
package provides the \includegraphics command which will take
as an argument the name of figure file and place a \special command
in the dvi file listing the name of the file, its dimensions, and
other information. Although TeX itself knows nothing about figure
files, most dvi printer drivers (such as dvips) know how to
interpret the \special information and will insert the figure.
You can tell dvii to go through a dvi file and list the location and
contents of each \special. This can be useful, for instance, if you
want to see on which page a particular figure appears without actually
viewing or printing the file.
dvii -s test
s:[2/2]:: A short special
s:[3/3]:: abcdefghijklmnopqrstuvwxyzABCDE...
s:[4/4]:: PSfile 1.eps
s:[4/4]:: PSfile 2.eps
s:[4/4]:: PSfile 3.EPS
s:[4/4]:: PSfile dog1.gif
s:[4/4]:: PSfile cat.eps
s:[6/-3]:: Some control characters: []