Looking for information on the UnicodeData file

[Pim Blokland]

I apologize if this question has been asked before, but I'm relatively new at this. My question is: where can I find formal definitions of the terms used in the Character Name field of the UnicodeData.txt file? Most specifically, precise explanations of designations like "turned", "inverse", "inverted", "reversed", "rotated" etc. Also the difference between "digraph" and "ligature", etc. Although I've searched the FAQ files and the rest of the unicode.org site, I haven't been able to find this info as yet. This site is huge! So can anyone provide me with an URL? Thanks.   Pim Blokland