Import marks

When did import marks become manditory. I have a k98 with the Nazi marks removed without any import marks.

Can't comment on the exact time import marks were required; however, many countries removed the Nazi markings from K98s and other captured weapons.

Thanks Capt03 Im doing some research on it now
Its Has 1936 S/243 on the reciever

OK i found this
There are a number of reasons an import mark may not be present. The most common reason is the mark wasn't required at the time the rifle was imported (1968 & prior). Many countries do not require it, America didn't require it until 1968, rifles brought home by the military and sold as surplus, carbines brought home by individual soldiers.