I learned from the ‘Form programming’ video that one prefixes the name of a procedure with the T-square symbol in order to add it to the Construct menu. Fine, but I have searched Unicode for the T-square symbol and find it nowhere. Can someone please advise me on this?
It is actually an emoji, you can find it in Edit>Emoji & Symbols
You can also probably copy it from here, though I’m not 100% sure whether emoji’s copied from this forum page will work or not: 📐
If you come up with something cool that works in the Construct menu I’ll bet many hear would like to hear about it. I know I would 
They will if you set them off in backticks so that the forum reads them as code, but if you just put them in the ordinary text, it will replace them with a picture of the emoji.
I edited Jim’s answer so that the triangular ruler 📐 is set off in backticks and can be copied from the forum. The smiley is still a picture.
The Unicode number is U+1F4D0.
Thanks, Jim and Dave, for your help. I found the triangular ruler system at U+1F4D0, as Dave said, and it’s working. In Jim’s form programming video it’s already in Favourites, and that’s where I now have it. I’m just following the video through and trying to replicate everything so that I understand it.