OpenXcom / github palette folders ?

[Skybuck]

https://github.com/MeridianOXC/OpenXcom/tree/oxce-plus/bin/common/Palettes

What is the difference between these folders and what are their purpose ?

UFO-ACT-SAFE
UFO-JASC-SAFE
UFO-JASC
UFO-RIFF-SAFE

(I tried one of the battlescape palettes, forgot which one, probably act-safe. I noticed the first color is set to green, which looks out of whack, seems more like it should be white, but now I understand it was set to green to indicate this is the transparent color. However it could be set to any color because it will be not drawn anyway. (For my purposes, interpolation/extrapolation white seems better, was green actually set by OpenXcom programmer, or did original ufo palette actually set it to a different color ?))

[Meridian]

Difference between ACT, JASC and RIFF is the file format... ACT is for photoshop, JASC for irfanview and RIFF is for coreldraw I think. (Or any other programs able to use them of course.)

Difference between SAFE and "not SAFE" is that SAFE versions have reserved indices replaced with dummy colors.
For example transparent index is replaced with bright green; dynamic background colors are replaced by bright magenta, unused indices are also replaced with bright magenta I think, etc.

Their purpose is to provide palettes for modders.

Original Xcom palettes are in the "not SAFE" files, taken directly from original Xcom resources (palette files and the executable). Of course they are converted to 255/xFF, since the originals were 63/x3F (see https://www.ufopaedia.org/index.php/PALETTES.DAT for explanation).

The SAFE versions were created by me.