There are units that take in guys especially like yourself, i.e. never get call up in many years and think that you have been forgotten, and quite likely not finish the reservist obligation before 40; so not forgotten just in a list and your name is at the top. What's the actual wording in your SAF 100 that says you should report in? If just no. 4 should be a 1 day affair right, I guess should be ok to report in old no.4 I've seen people reporting in that. Ops manning means cannot go overseas and be contactable within the stated period if I'm not mistaken.