Those three identifiers are by no means the only items that are not in the current help file.
Some items are missing due to human error (ie: they were forgotten to be entered), others are missing due to the fact that they have been superseded by other commands/identifiers.
I used to have an address for a supplemental help file that had most, if not all of the missing items in it, but, if I recall correctly, it was only updated as of 6.20
If I can find the address again, I will confirm that it's still valid, and if it is, post a reference to it.