\DeclareFontEncoding ¶Synopsis:
\DeclareFontEncoding{encoding}{text-settings}{math-settings}
Declare the font encoding encoding. It also saves the value of
encoding in \LastDeclaredEncoding
(see \LastDeclaredEncoding).
The file t1enc.def contains this line (followed by many others).
\DeclareFontEncoding{T1}{}{}
The text-settings are the commands that LaTeX will run every
time it switches from one encoding to another with the
\selectfont and \fontencoding commands. The
math-settings are the commands that LaTeX will use whenever the
font is accessed as a math alphabet.
LaTeX ignores any space characters inside text-settings and math-settings, to prevent unintended spaces in the output.
If you invent an encoding you should pick a two or three letter name starting with ‘L’ for ‘local’, or ‘E’ for ‘experimental’.
Note that output encoding files may be read several times by LaTeX so
using, e.g., \newcommand may cause an error. In addition, such
files should contain \ProvidesFile line (see Class and package commands).
Note also that you should use the \...Default commands only in a
package, not in the encoding definition files, since those files
should only contain declarations specific to that encoding.