What does CAL mean on a World War 1 military pin that has two crossed rifles?

I'm not certain what CAL designates. Typically, anything extra, numbers and/or letters is a unit designation. The crossed rifles, however, is specifically the symbol of Infantry. It can be nothing else. Crossed sWords is Cavalry, crossed cannons is Artillery, the Caduceus is Medical, a flaming bombard is Ordinance, crossed semaphore flags is Signal/Communications.