...half past a monkey's ass a quarter from it's balls. COL=overall length of a completed live round. Typically shown as a minimum spec. in relation to maximum powder charge. It does not dictate what is gonna be most accurate in your gun, just what minimal length is considered safe based on a maxed out powder charge. Generally never a consideration when working below a maximum charges.
My Lyman manuals call it Trim-to Length while my Hornady manuals call it "Case Trim Length" but my Speer manuals don't call it anything, it just has a pic with dimensions. I'm sure another source might call it case Length, take your pick.