Incorrect chapter numbering in PDF from DITA

Hello,

I am converting my unstructured FrameMaker manuals to DITA using FrameMaker and learning DITA along the way. The end result should be PDF documents.

FM version 17.0.3.546.

When I use the Publish function in FM to create a PDF, headings at level 3 become level 2 (1.1) instead of 1.1.1. Levels 1 and 2 get the correct numbering. The headings at level 3 are titles in topics linked to level 2 Chapter elements using topicrefs.

I understand that FM converts DITA files to a temporary .book-file during PDF-conversion. If I save the DITA bookmap as a book with FM components, I can see that level 3 headings are converted to paragraph format title.1 in FM’s Paragraph Catalog. I guess this is the origin of the problem, but is there any way to prevent this?

I have created my own PDF templates based on FM’s templates in Publish settings, Outputs, DITA template. I ticked the box “Save PDF via Book with components route” under DITA options.

Thank you in advance!