Macros and environment variables

The main key-combinations that you should know to write style files are the following:

M-i =

creates a new assignment. The first argument is a new command name and the second argument an expression.

M-i w

permits to locally change one or more environment variables. With statements are of the form ⟨x₁|a₁|⋯|x_n|a_n|b⟩, where the x_i are the names of the variables, the a_i their local values, and b the text on which the local environment applies.

M-i m

creates a macro. Arguments to the macro can be inserted using the tab-key.

M-i #

get the value of a macro argument.

M-i v

get the value of an environment variable.

M-i e

expands the macro with zero or more arguments.

More precisely, when evaluating a macro expansion {a|x₁|⋯|x_n} created by M-i e, the following action is undertaken:

• If a is not a string nor a macro, then a is evaluated once. This results either in a macro name or a macro expression f.
• If we obtain a macro name, then we replace f by the value of the environment variable f. If, after this, f is still not a macro expression, then we return f.
• Let y₁,…,y_n be the arguments of f and b it's body (superfluous arguments are discarded; missing arguments take the empty string as their default value). Then we substitute x_i for each y_i in b and return the evaluated result.