Are PrCs for spellcasters spellcasting classes?

[Uncle Pine]

This have probably already been discussed, but I can't seem to find anything (probably due to the fact that "spellcasting", "PrC" and "spellcaster" are really bad searching terms): are PrCs for spellcasters, in other words PrCs with "+1 level of existing arcane spellcasting class" or "+1 level of existing divine spellcasting class" (or both), considered spellcasting classes? "Spellcasting class" doesn't seem to be a RAW-defined term, as it doesn't appear in the glossary, but I may have missed something.

I'm not interested in PrCs with their own spellcasting progression (i.e. Trapsmith, Ur-Priest), I'm asking specifically about PrCs that advance spellcasting (i.e. Mystic Theurge, Rainbow Servant).

[Kristinn]

The rules are actually quite clear-cut. A spellcasting class is a class with a class feature called "Spells" in the class description. Simple as that. Only exception is a class that cannot cast any spells until later levels (Paladin/Ranger). As such, a Paladin 3 is considered to have no levels in a spellcasting class, while a Paladin 4 does.

A class feature which advances another class's spellcasting is not a class feature called "Spells". So for example if you have levels in Wizard, Cleric and Mystic Theurge, and then take levels in Initiate of the Sevenfold Veil, you can choose to advance the class feature "Spells" of either the Wizard or Cleric, but not the dual progression of Mystic Theurge, as it is not a spellcasting class.

[Uncle Pine]

The rules are actually quite clear-cut. A spellcasting class is a class with a class feature called "Spells" in the class description. Simple as that. Only exception is a class that cannot cast any spells until later levels (Paladin/Ranger). As such, a Paladin 3 is considered to have no levels in a spellcasting class, while a Paladin 4 does.

Do you have any reference? I dug quite a bit and didn't find any clear-cut rule. For example, PHB doesn't say that Paladin isn't a spellcasting class until 4th level. What it says is:

Through 3rd level, a paladin has no caster level. At 4th level and higher, her caster level is one-half her paladin level.
Caster level differs from spellcaster level (although the two coincide if you play, for example, a straight Wizard 20). Practiced Spellcaster pumps your caster level, while Mystic Theurge and other classes advances both, etc.

[nedz]

The rules are pretty vague on this issue — to the point of near silence.

There are two interpretations: and the one which says that these classes are not spellcasting classes results in less cheese.