also: http://www.watto.org/extract/program/archives.txt

+0  4 XPR1
+4  4 file len
+8  4 data start (special case when == file len, unknown format ...)
+C  4 file count
+10 4 ?
+14 (file count * 2 dwords)
    +0 4 name offset (+12)
    +4 4 data offset (+12) -> file data (not mips)
+?? 4 = 0

File data:
+0  4 data size
+4  4 ?
+8  4 data offset (+ data start)


07 01 00 00 (size in dwords)   XX XX XX XX (offset)

NN NN MM MM -- NNNN = size in dwords, MMMM - number of extra dwords

N words:
2
4 - offset at [3]
5 - offset at [1]

-------
Malcolm_pb.xpr - ?? large header (some, but not all *_pb.xpr files ??)
Malcolm_Team_pb.xpr
Lilith_Team_pb.xpr

in this format Hdr.FileLen == Hdr.DataStart
possibly, texture data goes immediately, Hdr[i].DataOffset -> texture (some hdr + short[], hi-byte of
each short is 0,1,2)

I was not found any UTX, which uses *_pb textures
Used from Engine.u/LevelInfo.PrecacheMap.Function
  (pb contains external data for animations and meshes)