If the option -T is specified and you have CPANPLUS installed, modules that are part of an earlier module's distribution with be denoted with S; modules without a distribution name on CPAN are marked with ?.
Also, if the -B option is specified, module belongs to a perl distribution on CPAN (and thus uninstallable by CPAN.pm or CPANPLUS.pm) are marked with C.
Finally, modules that has loadable shared object files (usually needing a compiler to install) are marked with X; with the -V flag, those files (and all other files found) will be listed before the main output. Additionally, all module files that the scanned code depends on but were not found (and thus not scanned recursively) are listed. These may include genuinely missing modules or false positives. That means, modules your code does not depend on (on this particular platform) but that were picked up by the heuristic anyway.