I don't know if anybody else knew this, so if you read this and decide you already knew it and this is old news, don't reply just to say so.
My new plug-in, Galactic Federation, is going to be pretty big, and I like systems that have the chance to change into heaps of systems. But only having one visbit field, I couldn't figure out how to do it without having systems overlapping. The solution is simple, and is the reason i might run out of mission BITS. Not IDS, BITS. Are there 512? or 256? I forget.
Anyway, here's the solution: (if anyone cares)
In the original system, the one there when u start the game, just put in the normal clear idea. (1011 for example). Now, if you've got two systems that it could change into, go into the 2 missions that change the system (1 for each possibility), and set them BOTH to set that bit (11 in this example). Then just set each mission to set another mission bit each (12 and 13), and put those into the new system visbits.
If anyone else knew that or posted it before me, sorry. But surely someone finds it useful.
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Three years and my pizza still isn't here.
Maybe I should call.