Tom, these are html pages, and the UBB codes are shortcuts for html coding. As far as I know nobody has programmed a UBB code for indenting. But you can use the html code to insert a lateral space:
BANNED POST You enter the code as many times as you want spaces. The code itself will disappear and leave a space behind it, which makes it tricky to edit afterwards.
BANNED POST "How," you will ask, "did you make the code appear in your reply?"
BANNED POST Svein showed me the code within the code.