I have found what appear to be a couple of bugs in TL5.33.
1) If you turn on protection for all of your custom functions, function 1 remains accessable.
2) A program which references the same custom function twice will compile and run, although the function runs every scan whatever the preceeding logic.(I know you shouldn't do this, but I did it accidentally when testing some logic)
3) If I program a free running timer, i.e. one which is activated by an NC contact the same name as the timer, contacts which reference the timer work when they preceed the timer, but not following. I know this is just a quirk, but with every other manufacturer's PLC the contact will remain on for one complete scan, so it works wherever it appears in the program.