PCX File Format Version number:
The PCX format is an early format which uses the RLE minimal compression technique. This is a good compression because to decompress a file the needed information can be found in the preceeding bits not in any following bits.
The PCX image format is one of the oldest raster formats. It was originally designed by ZSoft to be used by PC Paintbrush for MS-DOS. Microsoft later acquired the right to use the PCX format for Microsoft Paintbrush for Windows indirectly increasing the format's popularity. Since this format has been around for a long time, there are now many versions of PCX.