\DeclareSymbolFont {<sym-font>} {<encoding>} {<family>}
{<series>} {<shape>}
If this is the first declaration for <sym-font> then a new symbol font with this name is created (i.e. this identifier is assigned to a new TeX math group).
The arguments <encoding> <family> <series> <shape> are used to
set, or reset. the default values for this symbol font in all
math versions; if required, these must be further reset later for
a particular math version by a \SetSymbolFont command.
Checks that <encoding> is a declared encoding scheme.
For example, the following sets up the first four standard math symbol fonts:
\DeclareSymbolFont{operators}{OT1}{cmr}{m}{n}
\DeclareSymbolFont{letters}{OML}{cmm}{m}{it}
\DeclareSymbolFont{symbols}{OMS}{cmsy}{m}{n}
\DeclareSymbolFont{largesymbols}{OMX}{cmex}{m}{n}
\SetSymbolFont {<sym-font>} {<version>}
{<encoding>} {<family>} {<series>} {<shape>}
Changes the symbol font <sym-font> for math version <version> to <encoding> <family> <series> <shape>.
Checks that <sym-font> has been declared as a symbol font, <version> is a known math version and <encoding> is a declared encoding scheme.
For example, the following come from the set up of the `bold' math version:
\SetSymbolFont{operators}{bold}{OT1}{cmr}{bx}{n}
\SetSymbolFont{letters}{bold}{OML}{cmm}{b}{it}
\DeclareSymbolFontAlphabet {<math-alph>} {<sym-font>}
Allows the previously declared symbol font <sym-font> to be the math alphabet with command <math-alph> in all math versions.
Checks that the command <math-alph> is either already a math alphabet command or is undefined; and that <sym-font> is a symbol font.
Example:
\DeclareSymbolFontAlphabet{\mathrm}{operators}
\DeclareSymbolFontAlphabet{\mathcal}{symbols}
This declaration should be used in preference to
\DeclareMathAlphabet and \SetMathAlphabet when a math alphabet is
the same as a symbol font; this is because it makes better use of the
limited number (only 16) of TeX's math groups.
Note that, whereas a TeX math group is allocated to each symbol font when it is first declared, a math alphabet uses a TeX math group only when its command is used within a math formula.