A demolition charge or demo charge is a man-portable explosive.
In CMBN (CMx2 generally?), demo charges are used to blow holes in obstacles. This is done via the blast move command. The particular obstacles which may be holed (and thus, traversed) via demo charges are:
- walls (tall or short, stone or brick)
- bocage (short and tall)
- building walls (exterior and interior)
- barbed wire
In addition, demo charges can clear minefields as a side-effect of blasting any of the obstacles above. (As of 1.01, minefields themselves cannot be targeted for a blast.) Demo charges cannot be used to clear hedgehogs.
One blast will always create a hole large enough to allow infantry to traverse the obstacle. Vehicles may require larger holes; creating a hole large enough may require two (or even more?) blasts. Generally you should be able to see on the battlefield view whether a particular vehicle will fit a particular hole. If a vehicle drives up to a hole and then fails to traverse it going Slow, often doing odd turns or other moves that you didn't explicitly order, then the hole is not large enough. Blast it again.