Document structures that can not be represented with portable text

[runeh]

As far as I can tell, there is no way to represent nested blocks in portable text. This means that it's not possible to represent the same kinds of lists in portable text as in markdown. A markdown list item can contain a code block, or multiple paragraphs, which portable text can not.

There are bound to be some more cases like this. Would be useful if there was a place for it in the spec, or in an implementors guide.