As described in chapter 4, page 357, unit description files (hereafter called PPU files for short), are used to determine if the unit code must be recompiled or not. In other words, the PPU files act as mini-makefiles, which is used to check dependencies of the different code modules, as well as verify if the modules are up to date or not. Furthermore, it contains all public symbols defined for a module.
The general format of the ppu file format is shown in figure (A.1).
To read or write the ppufile, the ppu unit ppu.pas can be used, which has an object called tppufile which holds all routines that deal with ppufile handling. While describing the layout of a ppufile, the methods which can be used for it are presented as well.
A unit file consists of basically five or six parts: