Numbering System for Openings

Can anyone tell me where the numbering system for openings comes from? I'm talking about stuff like: the 150 attack, which I think is the Pirc.

Anyone?

I think that the name 150 Attack is a joke. The reference is, that the attack is so easy to execute that a 150 Elo player can beat black. This isn't real is simply a joke. 

The numbering systems of openings are the ECO system and are alfanumerical. A Uppercase letter (A, B, C, D or E) and two numbers to clasify diferents openings, and variants. Enciclopaedia of chess openings

The problem is the system is previous to the exploit of computer and database chess era and some modern variatons don't have suficcient room.

Sorry for the level of language, I'm bad in english.  

I'd read that that attack is so simple, only a 150 BCF player would try it hoping it works.

Which is something like 1800 elo.

So what exactly is the idea? I'm thinking it's the Q+B battery against h6, but that can't really be considered such that only an 1800 would play it, would it?

Silly british nomenclature... it can be safely ignored.

Not that it's a bad idea, and it certainly is an attacking idea, but I think the sentiment is that it's such an ordinary attack that you'll never catch an experienced player off guard.  It will never end the game in 20-some moves (as it probably would against most inexperienced pirc players).