Oxygen XML Author not finding DTD from DOCTYPE declaration

[ann.jensen]

Hi,
We use Tridion Docs bridge in Oxygen XML Author to open topics stored in Tridion Docs CMS.
This resolves and locates the dtd in C:\Program Files\Oxygen XML Author 23\frameworks\trisoftdita\
However, if I download a DITA topic from CMS and store locally, open it up then the dtd is not found.
I have updated Options-Preferences-Document Type Association to only select the related Tridion Docs document types but Oxygen is still trying to find the dtd referenced in DOCTYPE by looking in same folder as downloaded topic. What is the logic behind this and how can I tell it to look in C:\Program Files\Oxygen XML Author 23\frameworks\trisoftdita\ for the dtds?
Thanks in advance,
Ann

[Radu]

Hello Ann,
Officially we no longer support Oxygen 23 in any way:
https://www.oxygenxml.com/eol.html
Coming back to your question, once a plugin is installed in Oxygen, it may alter Oxygen's behavior in ways that Oxygen no longer controls.
For example we have an API which allows a plugin to resolve references to DTD directly in the plugin's custom code.
By default, without any plugin installed, Oxygen uses its XML catalog support to resolve DTD public IDs to DTDs, and when its XML catalog support does not find a DTD public ID mapping, Oxygen will fallback on searching for the DTD in the same folder with the XML document (by following the DTD system ID relative reference which is usually "topic.dita"). For example in the Oxygen Preferences->"XML / XML Catalog" page you can enable "Verbosity->All messages" and then validate a DITA XML topic and Oxygen should log in a messages view about what XML catalogs it loaded and how it attempted to resolve the DTD public ID.
Regards,
Radu