OK, got the triangles working. Now I'm working on what users might put in, even if they get it a bit wrong.
For example, you wanted LLLE scrapped, but this can still be interpreted unambiguosly, so now the code accepts it, but re-writes a 'standardised' version LLEL to the sheet. The same applies to LLTI; it becomes LTIL. There are several more…

This has brought up something else. I'd like to know a bit more about what LE and TI actually are (in the real world), so a bit of narrative on those please.

• Is LE something that can happen EITHER in the morning OR in the morning on the same day?
• Can LE happen BOTH in the morning AND the afternoon?
• If LE happens does it automatically exclude one or more of the other things (L,X,C,TI or anything else) happening on the same morning/afternoon/day? If so, which things?

The same for TI:

• Is TI something that can happen EITHER in the morning OR in the morning on the same day?
• Can TI happen BOTH in the morning AND the afternoon?
• If TI happens does it automatically exclude one or more of the other things (L,X,C,LE or anything else) happening on the same morning/afternoon/day? If so, which things?

Could you give an answer to each/all of the bulleted points please.
I'm sorry to ask you so many questions - I'm just trying to make this as useful and robust as possible.