[Export idml file]

1 hour ago, mac_heibu said:

As I said: Do it and life with the consequences!

Just to demonstrate: In the attached screenshot you see a (quick and dirty) InDesign layout using column span, column balancing, paragraph boxes and lines, column separator, multi column tables, footnotes.

You see: There is no way to convert this file correctly, because there is no feature parity between the source- and the destination app. Even text flow can’t be correct, because different algorithms are used. This, by the way, is true in the exact same way, if you transfer IDMLs between different version of InDesign.

So again: IDML is a fine format to transport a document to a different (version of an) app, and continue and finish your work there. But it never is a viable strategy for perpetual interchanges between co-workers using different applications.

I also attached the IDML file exported from InDesign 2020 (15.02.), so everybody can test it.

Indd-Test.idml 47.15 kB · 0 downloads

You might not see the logic in it, and how it could be of any use for you, and that's okay.
But it could also help plenty of people out there.

The company I work for, we all work on inDesign but all on different versions (some even run on CS6 to avoid paying monthly), so we use IDML files anyway. Once we finished our part, we send the idml file to the person who will take care of comping everything, adding the final touches, and making the final project print ready. 
In such instances, there WILL be changes made by the person taking care of the final steps. So knowing that, there would be no issue for us to have IDML files exported from Affinity Publisher. Some of us are even waiting for an idml export feature to switch to Affinity. 

It's not because the export would not be perfect that it means it cannot be useful.

[Export idml file]

I agree, exporting to IDML would be the feature making me switch to Publisher. In my job, being able to export to inDesign format is mandatory.

I hope exporting to IDML will eventually be possible, because that all I'm waiting for to switch from inDesign to Publisher.