FWEAVE can check module names for the possible anomalous conditions of “never used” or “multiple uses.” These correspond to a module warning level, as in the following numbered list:
The module warning flag is the bitwise OR of the desired warning levels; warning messages are printed only when the relevant bits are turned on. By default, it is 1, so only messages about never-used modules are printed. The ‘-W@flag’ overrides the default. For example, to get messages only about multiple uses, say ‘-W@2’; to get no messages, say ‘-W@0’. One can put such an option into the .fweb initialization file (see Initialization).
FWEAVE will always complain about module names that are never defined.