[brookst]

A 15 minute shift once every hundred years would wreak havoc on all of the software built when the shift was too far away to worry about.

Better to design in the requirement for all software to support these shifts, like a random 10 minute shift every day. That way nobody will write software that doesn’t support the shift.

[toast0]

Timezone aware code already has to process 15 minute timezones, IIRC; India is on a 30 minute timezone.

Some timezone changes are well published before the change and others are published after, and software has to pick up the pieces.

I'd imagine a 15 minute jump to recenter zones would be published with at least as much notice as changes to DST rules.

[hermitdev]

AFAICT from looking at the source for the tz database [0], it's capable of handling UTC offsets at least to a second level, if not fractional seconds.

[0] https://github.com/eggert/tz

[fanf2]

ISO 8601 and other display standards for timezones only support one minute resolution.