NAMES are very potent in Fantasyland.

People with no Names always get killed (unless they are powerfully EVIL and have a Name That Must Not Be Spoken, in which case they get killed anyway, but a lot later).

Of those who have Names, almost nobody tells anyone else what their Name really is, for fear of its being used in a SPELL to enslave them. MAGIC USERS have to be particularly careful of them. But MERCENARIES also tend to call themselves things like Bald Eagle and Silversword, presumably for the same reason (or maybe because their true Names are Joe Coward and Jill Doe).

MISSING HEIRS are always called Names like Triggs and Dumpling: when they find their Names are really PRINCE Tornalorn or PRINCESS Diore, they stop being MISSING. This shows how important Names can be.

AVERAGE FOLK, SAGES and some Tourists, however, adopt the expedient of cutting out half their Names and filling the gaps with APOSTROPHES, as in Ka'a Orto'o. Then, unless you know what was in the gap, you can't enslave them. This is the true reason why so many Names in Fantasy Land contain Apostrophes.

Many folk - ELVES and DEMONS particularly - are given hugely long Names so that they can be conveniently shortened in this way. Demons, indeed, would have a bad time otherwise. As soon as a Magic User learns a Demon's name, that Demon has to do anything the Magic User wants.

On some Tours the same prudent coyness applies to MAGIC OBJECTS. The exceptions are SWORDS, who seem very proud of being known to be really Excalibur or Widowmaker.

from the tough guide to fantasy land, by diana wynne jones.