VLAST (ASEC) vs. VWHEN (Veteran Supplement)

Hi, it seems that the semantic of these two variables is the same within their respective survey - namely, the period of most recent active duty service. Is this correct? Many thanks.

While these variables are similar, there are some differences. VETLAST, part of the ASEC, was asked of all civilians (or civilian males) of a certain age up until 2006, whereas VWHEN, part of the veterans supplement, is asked only of veterans, according to VETSTAT (see the universe tabs for each variable to see this distinction. The codes for these variables are almost the same, however, VETLAST includes codes for service during World War 1 or peacetime eras, whereas VWHEN does not.