You receive much information by means of subspace messages. Many programs attempt to read and understand (=parse) these messages to display them graphically. For example, programs will extract your mine laying/sweeping messages to show you your minefields on the map.
The main implication of this is that, if your client program relies on message parsing, you should not change the language of your messages, or your program will no longer understand them.
The Winplan RST format obsoletes some but not all message parsers (for example, PBPs still are only in the messages).
PHost sends you most information from messages also in machine-readable form in a file util.dat. Programs aware of that (and good programs are aware of util.dat) will display things even when they can't read the messages.
