Great, thanks! These are in no particular order: -R, --readonly: Inhibits the w, wq, and W commands.
-P, --prompt: Executes P command. (.,.) arguments to ! command: Process specified lines through the shell command. multiple files on the command line, N and R commands: You can specify as many files as you like, but normally only the first file is used. The N and R commands cause the next (or first) file in the list to be loaded as if by the e command; the newly loaded file name is printed. ("R" is for "rewind".) T <tag> command, -T/--tag option: Jump to a tag in the `tags` file in the current directory. Lines in a tag file look like "tagname<TAB>file<TAB>+-option". If "file" is not the same as the current file, it is loaded as if by "e". The + character is not included in the third field, so it is a line number or a search pattern beginning with / or ?. A semicolon and everything following it is ignored. U and R commands: U is multi-level undo, R is redo. J command: Same as j, but adds a space between original lines. F command: Enhanced version of f command. Displays values of . and $, and indicates if the current file is modified and/or readonly. x command: Equivalent to wq command. < command: Remove up to 8 spaces from beginning of line. > command: Insert up to 8 spaces at the beginning of line. (EOF) command: Same as z, but outputs half as many lines.