think about it like a clock without stating the actual time. the clock is based on 12 hours and everything you do is based on when you give the insulin and each hour after the dose until the next time to give the insulin.
For example, if you shoot at 8 am and 8 pm, your chart looks like this
AMPS - morning pre shot number - this is the test taken before insulin at 8 am
+1 - the test taken 1 hour after giving insulin
+3 - the test taken 3 hours after giving insulin
+8 - the test taken 8 hours after giving insulin
PMPS - evening pre shot number - this is the night time test taken before giving insulin at 8 pm
+2- the test taken 2 hour after giving insulin
+4 - the test taken 3 hours after giving insulin
+11- the test taken 11 hours after giving insulin
The colors on the chart red, green yellow, blue, black, represent the BG range the cat is in. We use colors to make it easier, if the cat is blue or green he's doing great and at a great level. If he is yellow, pink, red or black, his BG is high and if it remains this way over several days, a dose increase may be needed
As everyone is in different time zones, this "clock" was created so we can all follow what's going on with the cat. My 8pm is ET and the person who may look at my chart may be on the west coast and 8 pm means nothing to that person, yet, if I say the cat's BG is 390 at +3, everyone understands what that means and can help.
Make sense?