Modes:

1:  Timed
2:  Standard Game
4:  Survival
8:  Protect a unit
16: Defend a tile
32: Capture a tile
64: Destroy a unit

You can have combinations of modes, for example:

3:  Standard game with a time limit (if you don't win before time runs out, you lose)
40: Capture a tile while making sure a certain unit doesn't get destroyed


Important stuff:

A -DESCRIPTION- would certainly help.
If you have a -STARTINGCASH- entry, MAKE SURE IT HAS A NUMBER FOR EACH PLAYER
Make sure the -OPPONENTS- entry ends with a -1
If you have a -KILL- or -PROTECT- entry, make sure they're ended with a -1

For kill and protect entries:
Each entry is a number from 0 to 349, with the player number as the hundreds digit.
For example:
  Player 2's ninth unit (in order of placement in the map editor) is 108
  Player 1's first unit is 0
  Player 4's 50th unit is 349


If these requirements aren't satisfied, expect bad things to happen when loading the mission
