Impression was Computer Concepts Desktop Publishing program for RISC OS. I spent a lot of time trying to write a better DTP program. Beebug for whom I wrote the Ovation DTP program were wary of upsetting Computer Concepts, we would often do things in a worse way rather than copy Impression features. Eventually when Beebug departed, I decided to have go at writing code that would convert an Impression document into Ovation Pro DDL.
I thought it would be difficult, a bit like cracking a code, but it proved straightforward. I had no inside information, just a copy of Impression and my trusty Acorn programmers' editor 'twin'. But having written a couple of DTP programs I had a good idea of what a document would contain.
The idea was that once Ovation Pro could load Impression documents everyone would love it and buy a copy. That's what they told me. In practice people found the inevitable compromises where Ovation Pro could not do exactly what Impression did and decided to stick with Impression.
The loader can handle both the single file Impression document format and the older folder based documents.
The code below should give you an insight into the Impression file format. Some Impression documents are corrupt, and a program to fix them could be written.