What does CPC mean in British shell terminology?

What does CPC mean, and how does it differ from a ballistic cap?

CPC means common pointed capped, but the wider distinction is complicated by inconsistent period and secondary-source classifications.

CPC expands to common pointed capped. British shell nomenclature is difficult because sources group the labels differently, sometimes under high explosive and sometimes as distinct common-shell categories. Service terminology also changed over time, so a neat one-line distinction from every kind of ballistic or armour-piercing cap would be misleading. A full taxonomy needs separate technical treatment.