I'm assuming you know and just didn't go into the detail that normal SI unit codes are from 31 and up and that numbers below 31 are reserved for special units like, start, finish, clear, check, etc?
Ha, I discovered the same just before Westerns. Led to some hasty renumbering of units... Personally I'd suggest changing your numbers to overlap with VicO or someone else you're unlikely to borrow units from. Otherwise every organiser/planner in the future will have to remember the "no SI-5" rule.
@Canadian. Yes I am aware, just didn't right it down. All cards (except maybe the p card of something?) accept numbers below 31 as special units. Regular punches are above that.
@bensmith. I've already got flagging out for those controls on the long, and won't have time to re-flag it all with NAOCs and the school starting up 3 hours from the event site. So I'm kind of stuck with using those numbers until the end of September. After BCOC this year I'll get the provincial numbers from OBC again and overlap the Revelstoke set with someone else, likely VicO. I don't think we've every shared units with them, other than possibly if GVOC borrows both for Sprint Camp.
I just checked through our rental SI stash, and turns out the ones I thought were SI 5 are actually SI 6.
Just a bit of a follow-up from BCOCs. We missed giving out newer SIs to a few of those with SI-5s (roughly 5% of competitors still used SI-5 - the most common reason being that they didn't want to memorize a new number). It's interesting to note that the punches are still recorded, just with the wrong number (eg it is the punch number minus 255). This meant that it was possible to recreate someone's splits from their punches. The biggest issue was that some of the numbers read overlapped with the usual start/finish/check numbers so you had to double-check that the start time was the assigned start time as opposed to the start time punch in the middle of the race :)