PHost needs turn files to be tightly packed, without gaps between commands. Essentially, it ignores the command pointers in the TRN header. If you send commands with gaps, PHost will get confused. (Note that this is considered to be a misfeature and will probably be changed someday. Still, it doesn't have high priority - why? the system works :-) There's only one small problem: the PlanetBuildBase command (34) has an irregular format, some people simplify their Maketurns by making it regular and including an additional data word. This works with HOST, but does not work with PHost!

PHost versions below 3.3b could get confused when you don't send commands in the canonical order (ships in Id order, planets in Id order, bases in Id order, messages, password; commands for each object in command Id order). PHost versions above that can recover from this problem, but up to 3.4a, they might shuffle messages around in return. Version 3.4b and later use The Right Way(tm).