I was studying some script command examples for the 'cloak of darkness' adventure.

What does this mean?
set variable object parent = expression player

(It's part of the Wear command)

I think what you mean is more or less something like this:

object.parent = player

If it's a part of wear command, then I suppose this is more or less what happens when player enters "Wear whateverobject". The reason player is in expression is, I suspect because "nickname" of the "player" itself may be changed, so in order for Quest to identify the player when this happens, it becomes an expression that goes after the "player" even if it's not called as "player". Technically it's kind of similar to go after its name instead of the alias.

Hope it helps.
Or I hope you get a better help soon >.<

Hi Y4T5UR0
Thanks for your attempt but I need a accurate answer rather than a "I suppose this is more or less what happens".

mrangel has answered this for me.