More flexibility for shortdesc element.
Expand the content model of shortdesc to make it equivalent to section; add a subelement to identify a portion of the shortdesc to be used for previews.
Alternatively, add a new element "abstract" that can be authored instead of shortdesc, and which can contain shortdesc (maintaining shortdesc's current processing model intact, but adding an optional container element that can hold a wider variety of content)
Minor
<topic id="x"> <title>My topic</title> <shortdesc><p>I can have paragraphs.</p> <previewpara>And also a special kind of para</previewpara> </shortdesc> <body>...</body> </topic>
<topic id="x"> <title>My topic</title> <abstract><p>I can have paragraphs.</p> <shortdesc>And also a special kind of para</shortdesc> </abstract> <body>...</body> </topic>
Changing the doctype to allow a new peer element of shortdesc similar to section, or changing the doctype to make shortdesc more like section but contain a more restrictive subelement.
Time to redesign the document types is minimal, and either option allows backwards compatibility.
Implementers will need to update logic for generating summaries and for selecting link previews.
Currently the different uses of the shortdesc put some pressure on the author, and can result in compromise introductions/overviews that are longer than strictly appropriate for a link preview, or shorter than would be useful for a generated summary.
2 meetings to agree on design.
ca. 1 week to update code.