There are various numbers, including the serial number, proofing marks, and caliber. Most Spanish Mausers were chambered in 7X57.
Usually the sn and caliber
Old
"anciano" in Spanish means "elderly" or "old person".
Old
Cuantos anos
old lady
old
It's an old-fashioned way of saying: Vi (I saw). From Latin "vidi"> old-fashioned in old Spanish "vide" > modern Spanish "vi"
very old
Antigua
Although many references have been published on Mauser rifles, I don't know of any that have a complete sn listing.
There is no Spanish word spelled "viego". However there is a word only one letter off "Viejo" in Spanish means old, or old man.