The command-line construction
-mA(x)=x
defines the FWEB macro A as though the definition
@m A(x) x
had appeared in the first definition part of the web file.
One can also say ‘-m'A(x) x'’, where the quotes are removed by the shell. That is, an ‘=’ appearing immediately after the macro name (or argument list, if there is one) plays the role of the space in the conventional definition. Thus, carefully distinguish the forms
-m'A(x)=x' // A(x) expands to ‘x’ -m'A(x) =x' // A(x) expands to ‘=x’ -m'A(x)==x' // Precisely equivalent to the previous example.
The equals sign is permitted only with command-line macro definitions, not with ‘@m’ commands (see ATm) in the definition parts of the web file.