Internal Program Version:  JBIG-KIT 2.1  (The HEADER-Files)

JBIG-KIT provides a portable library of compression and decompression
functions with a documented interface that you can include very easily
into your image or document processing software. In addition, JBIG-KIT
provides ready-to-use compression and decompression programs with a
simple command line interface (similar to the converters found in
netpbm).

JBIG-KIT implements the specification:
    ISO/IEC 11544:1993 and ITU-T Recommendation T.82(1993):
     Information technology - Coded representation of picture and audio
     information - Progressive bi-level image compression

which is commonly referred to as the "JBIG1 standard"

http://www.cl.cam.ac.uk/~mgk25/jbigkit