The PR looks good. I'm a bit hesitant about this feature, because I don't see the benefit of using a single column over multiple columns. Can you describe your use case? Is it that your single AP column might contain many different annotation properties?

I'm still having trouble seeing the use case for this, but I'm not opposed to it. Can you please complete the documentation for this feature in template.md?

I'd like to see this capability added. We use dozens of annotation properties for curation and domain specific descriptions but an individual term is likely to use only a small number (but necessarily the same ones in a batch). Putting both the property and literal into a single pipe-separated field keeps us from maintaining very wide but sparse spreadsheets and we don't have to change the template when we add new annotation properties.

Thanks @dlutz2. Have you used or tested this PR?

We've been using the multi-annotation capability in production since it was proposed. Been working fine.

I made some changes and generalizations to this in #1249 Please take a look.