Hi Adrian, Thanks for that. I found the error. I decided to do the same on another PC that had version 11.0. That version complained about IMPLIED. It turned out that I used "IMPLIED" (incl quotes) instead of #IMPLIED when I added an attribute. It is still strange that two 12.2 versions re...

I have a certain DTD, version 5.1.0. I use the catalog to find it and validate against it. The new version v5.2.0 is backwards compatible. In the catalog I copy the 5.1.0 line and change the 1s into 2s. Then I open a 5.1.0 file and change the 1s into 2s. Validation then gives this error: SystemID: C...