ppudump is a program which shows the contents of a Free Pascal unit. It is distributed with the compiler. You can just issue the following command
ppudump [options] foo.ppu
to display the contents of the foo.ppu unit. You can specify multiple files on the command line.
The options can be used to change the verbosity of the display. By default, all available information is displayed. You can set the verbosity level using the -Vxxx option. Here, xxx is a combination of the following letters:
Show header info.
Show interface information.
Show implementation information.
Show only (interface) definitions.
Show only (interface) symbols.
Show browser info.
Show everything (default if no -V option is present).