RawGfx mode's Palette Panel supports to load and save palettes in a number of file formats.
Raw Byte Tripplets
The file is a raw dump of RGB byte tripplets, 24-bit RGB in little endian byteorder. The RGB-color definitions are mapped into the palette starting at color index 0.
There is no requirement on the number of colors defined, as long as the filesize is a multiple of 3.
RISC OS Palette
RISC OS Palette files contain palette definitions in the form of Acorn BBC Micro VDU (Video Display Unit) control codes. This format is commonly used on Archimedes and RiscPC computers running RISC OS or Arthur OS.
Without any file header, the palette is defined as a concatenation of 6-byte sequences:
0x13 CC 0x10 RR GG BB
0x13 CC 0x10 is the VDU control code sequence for the RGB-mapping of a logical color index. CC is the color index. RR, GG, BB are 3 bytes of RGB-color definition in 8 bits per channel.
There is no requirement on the number of colors defined, as long as the filesize is a multiple of 6 and well-formed.