Looking something like electrical flex Detonator Cord1 is actually a strip of high explosive in a protective plastic wrapper. The NATO version is (or used to be) filled with PETN2 and comes in any colour that is white. There may be other versions by now.
Note that det cord filler is usually3 a secondary explosive (usually a fairly stable one) and needs to be fired with a detonator in its own right. You can probably4 burn the stuff like fuse match if you're that bored.
The intended purpose of det cord is to propagate an explosion more or less instantaneously over distance - for example, if you have a series of charges that you want to fire all at once you rig them all and prime each of them with a detonator crimped off to a length of det cord. You then tie off all of the detonator lengths to a single main line, also of det cord and fire that with its own detonator - if you do it right the firing of the top detonator will be propagated pretty much instantaneously to the detonators in the charges and the whole lot should go up as one.
Sappers being what they are, other uses have been found - it's a quick, if expensive way of cutting tree branches, pipes and the like5 and of shearing through mesh fences and barbed wire tangles6. Allegedly, once these uses have been demonstrated to a captured illegal combattant, he will become a lot more co-operative if you put a loop of it7 around his neck - obviously this shouldn't be done to proper POW or detained civilians though.
Game and Story Use
- Another toy for PCs. Also a useful detail to prove the GM has done his research.
- Possibly you could smuggle det cord disguised as rolls of electrical flex …