Hi,it's actually a table in a military service certificate, with two columns of dates: when he started to serve and when he ended. I was thinking of translating ALTA as CHECK IN and BAJA as CHECK OUT. How's that?
I agree completely. Check in/out and on/off duty refer to daily situations (e.g., I am on duty at 0800 and off duty at 1600).Given your context, no... "Check in" and "Check out" don't really convey the true meaning.
In the US, the date somebody begins military service is usually called their induction date. The date they end their military service is called their discharge date.