Questions about account types for user accounts

[Calek]

Alright, by account type I mean WoW, WoW:BC, or WoW:WOTLK.

This question is about the Emulator Ascent.

On this server, account type '0' is World of Warcraft.
Account type '1' is Burning Crusade
Account type '2' is invalid. It's not a WOTLK server, I assume if it were..that would be the account type.

Here's the thing..using letters works for the account type, but naturally since it's a number only entry, any letter sets the account to regular WoW "Account type '0'. But, account type '-0" works too, and allows creation of Draenei & Blood Elf.

What can type '-0' possibly be? Is it an entry that means "ANY CLIENT"?

I'm doing the best I can at giving enough information to get an answer..it's a very popular private server and I don't want it named.

**EDIT** I should also mention that the account type is being changed via a website, and not directly in the Database