This is inspired by a discussion on the Scattershot Forum:

Fang described his points in Scattershot as "particles of character class." I sort of disagreed with his definition--an indication to the GM of what your character is supposed to do/what you want your character to do (I don't think he's wrong exactly--but I think that by the mechanics alone, without the Techniques he's using, the fact that someone has points in a science skill doesn't mean it's primary to the character concept). Anyway:

I said that in modern day gaming, Character Class was sort of like a cross between profession/intent/and how the character fits into the world. In AD&D character class is a no-brainer. Even if it was skill based, point based system you'd still need a thief, fighter, magic user, and cleric on each adventure--the world just works that way.

In moden day it's less clear.

ALMOST TO THE POINT
I'm the author of a multi-genre RPG. It uses standard points to construct the character but there is also a pool of "Weird Stuff" or "Archetype" points (this isn't fully consistent across all of our material yet--but we're getting there).

So you might have 75pts with 32 Fantasy points (Archetype/race/weird stuff) points in a fantasy game (enough to play a Dragon PC).  Mostly these are special abilities (like a Knight can buy special 'Bloodline' inhereted armor or a thief can get some secret knife fighting moves, etc.)

THE POINT
Some of these special abilities are meta-game. Especially in the super's books (where we had serious trouble applying Archetype rules--for a variety of reasons). But, after defining what I thought Particles of Character Class (Fang's term) *should* be, I looked again at the file of supers archetype stuff.

Here is what I thought Particles of Character Class *ought* to be: something you buy for the character that in and of itself defines how he or she fits into the world. This is not purely deductive--it's prescriptive and has some ability for the character to enforce it. Here is an example of one of the Conventions we've got (paraphrased and slightly modified this morning on the train ride to work):

Signature Skill Convention (4pts from the Archetype pool)
The character has a Siganture Skill--sure, all skills can be useful but this skill is especially useful to the character. This is applied to a noncombat skill. The character must define three hooks (defined below). If the Signature Skill does *not* come up during a game session, the character gets a "plot point" (exchanged for an advantage in combat, automatically making a skill roll, avoiding a failure, etc.)

Example: Poison Oak (a super hero) buys Signature Skill for Botany (he is a botanist in California). This means that either Botany comes up in a meaningful way during the adventure or he gets a plot point. His hooks are people, places, or history that would call the skill into use:

Hook 1: Poison Oak is often called on by the Marine Botany Research Station.
Hook 2: Poison Oak has an arch-rival The Advocado Wrangler who is waging a botanical war against the wealthy Advocado farmers (and uses mutant plants!)
Hook 3: Poison Oak protects a secluded vinyard that has mutant intelligent grapes (created by a mad botanist).

Anyway, the example above is illustrative of what Character Class Poison Oak is since it determines what he does and how it fits into the world (if you look at his character sheet, he's a smart "Brick"). It also doesn't preclude him from going on large group adventures that don't spot-light him--he'll just get a plot point for those.

We've got several others (like Somebody Knows Something--conventions for a streetwise detective).

I'm putting this out here as some speculation on what Character Class is (I encourage you to look at Fang's Scattershot posts--he has some very interesting observations).

-Marco