I found a PDF online of a PPT on What's New in SELECTseries (1 or 2) which explains you can display cells for things like the top of structures in Profiles and/or cross sections. Is there some explanation of the steps needed to accomplish this. My experience with the structures.dat file is that the documentation of what can be done and how it is accomplished is limited to non-existent. Through a lot of trial and error I developed a version that meets our local DOT's drafting standards and also provided a way to show existing and proposed structures differently. But as far as showing a cell at the top of a structure - have not looked into it.
I found this PDF while searching at home and cannot replicate the search here at work, so I cannot give any more info, However, there were other items in that list that would benefit from a manual with examples, as I recall.
TIA