I'm contemplating joining a club for some group rides. This is posted on their website:

Groups are usually organized by speed and distance.

‘A’ groups are the fastest and longest (approximately 90-110km at an average speed in the low 30’s kph).
‘B’ is the intermediate group (60-80km at an average in the high 20’s kph), followed by
‘C’, the slowest (about 60km at an average in the low 20’s kph).

Within each category of A, B and C we may break the groups down into subgroups (e.g. A1, A2 etc). Our goal is to have groups of 8 to 10 compatible riders (with a maximum of 16).

So I'm curious, when they say average in the low 30's kph, is this the speed they normally maintain on flats, or is it like actual average, entire ride distance/total time?

Obviously, having never ridden in a group I'd start with Group C to learn the ropes, but I'm just wondering