I feel this is too library specific. The ordering of the list is non intuitive and seems specific to this library.

How about we store it like the iso standard instead as offset from UTC. We can store this as a single 8 bit signed value which is the offset from UTC in 15 min intervals.

A value of 0 would mean UTC. +1 would be +0:15, +4 would mean +1UTC, -8 would mean -2 UTC.