<pre>
00 4B last 4 bytes of the data (not compressed)
04 1W size of non compressed part at the beginning (usual always 0for SGX files)06 ?B not compressed part of the data(not existing in SGX files)
?? ?B compressed part of the data without the last 4 bytes
using the "ZX0 data compressor" by Einar Saukas, see