The Roman numerals are the Marks of your chargers.
The Mark II is a World War One charger, the Mark IV came into use during the Second War.
Broad Arrow, as always, indicates British Gummint property. Your chargers with the Broiad Arrow in a circle, if you look very carefully, likely will prove to have the Broad Arrow in a letter "C". This is Canadian Gummint property.
The "S" charger could possibly be Savage; I heard that they made a bunch but this could well be incorrect.
Hope this has been SOME use.