PHost 4.x supports up to 999 ships. The actual ship limit can be configured in pconfig.src (NumShips). When all players use appropriate client programs, you can use this to delay the ship limit a bit. See under NumShips for more information.
When there are less than 500 ships in the game, PHost generates files compatible with all client versions. Actually, PHost 4.x will always write "Host999-style" result files. None of the known unpack programs have problems with this. However, recent Winplan versions will always unpack results as if they were made by Host999, producing bogus scan reports, so this also works around that problem. PHost allocates ship Ids so that Ids above 500 are only taken when there are more than 400 ships in the game. This way, players can start the game with an "old" client and update later.
