This material hasn't altered in several years and is no longer being maintained. It is provided for historical use only.
The Psionics Files is my project for collating information about programming the Psion Series 3 machines which is not in the manuals provided with them.
OPOdump is a program for disassembling the contents of translated OPL files.
Links to other Psion information sites. These links may well no longer work.
The obvious first site to see is Psion itself.
On the other hand, while Psion Software plc looks somewhat of a disappointment, hidden under it is the EPOC World documentation pages, which include an online OPL manual.
Steve Litchfield maintains 3-Lib, and wrote Mapper 3a - a GIS for the UK.