If a web file is included via ‘@I’ (see ATI_), for example
@I formats.hweb
then the ‘-i’ option means to read and process the web file, but don’t print its contents. This option is often used for large files of macro definitions, formats, or typedef statements that must be included at the beginning of even very short web files; it clutters things up to print such header files all of the time. (C and C++ programmers will find that the ‘-H’ option substantially reduces the need to include such header files; see -H_.)
Note that files included via ‘@i’ (lower case) do not respond to ‘-i’ or ‘-i!’.
By default, identifiers that are referenced in non-printed include files are not cross-referenced or indexed in any way. To force them to be cross-referenced, say ‘-ix’ instead of ‘-i’. In the present implementation, the cross-reference information for such non-printed files is presented in the form ‘#n’, where n is the integer section number. (The LaTeX section label is undefined for sections in non-printed files.)
The option ‘-i!’ means skip the include files completely. This is usually not very useful.