Sometimes it is necessary to know the ID number of an element in order to perform some odd trick. One day I got so frustrated by not having this information, I downloaded the source code and laboriously compiled a list.
It is not necessary to do that now, but I do keep a list in a rather extensive reference folder in my TPT install folder. It is a spreadsheet in Open Office/Libre Office format, and a reasonably current version is available for download
It has quite a bit of useful information, though not always as complete and up-to-date as it should be. I will try to remember to upload an improved version now and then. My powdering has been erratic of late, due to my stronger obsession with origami.