Difference between GMT, GMT+0, GMT-0, GMT0 on Unix

Question

Under /usr/share/lib/zoneinfo

I can see the following 4 different types of info for GMT

GMT
GMT+0
GMT-0
GMT0

Are there any differences between these 4 types of GMT zone times? If so, what are the differences?

Answer 1

I think they are all the same, or at least have the same values.

Yoo can see all here: TimeZones

Answer 2

On my system (and likely yours as well), GMT, GMT+0 and GMT0 are all symlinked to GMT-0. So there is no difference.