Q:

How does PC-Lint (by Gimpel) look across multiple modules?

I'm using Gimpel's PC-Lint v8.00 on a C codebase and am looking to understand how it traverses modules.  The PC-lint manual only goes as far as to say that PC-Lint "looks across multiple modules". How does it do this? For example, does it start with one module and combine all related include files and source files into one large piece of code to analyze?  How deep does it search in order to understand the program flow? 
In a second related question, I have a use case where it is beneficial for me to lint one C module from the codebase at a time instead of providing every C module in a long list to PC-Lint.  However, if I only provide one C module, will it automatically find the other C modules which it depends on, and use those to understand the program flow of the specified C module?

A:

PC Lint creates some sort of run-time database when it parses your source files, noting things like global variables, extern-declarations, etc.
When it has processed all compilation units (C files with all included files, recursively), it does what a linker does to generate your output, but in stead of generating code, it reports on certain types of errors, for instance: An extern-declaration that has not been used, an unused prototype without implementation, unused global functions. These are issues not always reported by the linker, since the code generation is very well possible: The items have never been used anywhere!
The search depth can be influenced by the option -passes, which enables a far better value-tracking at the cost of execution time. Refer to seciton 10.2.2.4 in the PDF manual (for version 9.x).
To your second question, no, if you only provide one (or a few) source (C) file name(s) on your Lint command line, PC Lint will process only that file - and all include files used, recursively. You may want to use the option -u for "unit-checkout" to tell PC Lint that it only processes a part of a full project. Lint will then suppress certain kinds of warnings not useful for a partial project.

