The second example provided for the classlevel operator is classlevel("PC.Prestige"), however this doesn't actually work because neither PC nor Prestige are specific classes, they're types of classes, and so must be used with the TYPE= syntax, e.g. classlevel("TYPE=PC.Prestige").
The dot operator also appears to work inconsistently. classlevel("TYPE=PC.Prestige") appears to evaluate as classlevel("TYPE=PC") + classlevel("TYPE=Prestige") but classlevel("TYPE=PC.NPC") appears to evaluate as just classlevel("TYPE=PC"), while classlevel("TYPE=NPC.PC") evaluates as just classlevel("TYPE=NPC"). Tested using a Fighter 10 (TYPE:Base.PC), Sorcerer 1 (TYPE:Base.PC), Adept 1 (TYPE:Base.NPC), Arcane Archer 1 (TYPEC.Prestige) using the Pathfinder core rulebook data.
From the debug console:
classlevel("TYPE=PC") = 12.0
classlevel("TYPE=NPC") = 1.0
classlevel("TYPE=Prestige") = 1.0
classlevel("TYPE=PC.Prestige") = 13.0
classlevel("TYPE=PC.Prestige.NPC") = 13.0
classlevel("TYPE=PC.NPC") = 12.0
classlevel("TYPE=PC.NPC.Prestige") = 12.0
classlevel("TYPE=NPC.PC") = 1.0
classlevel("TYPE=NPC.PC.Prestige") = 1.0
classlevel("TYPE=NPC.Prestige") = 1.0
classlevel("TYPE=NPC.Prestige.PC") = 1.0
classlevel("TYPE=Prestige.PC") = 2.0
classlevel("TYPE=Prestige.PC.NPC") = 2.0
classlevel("TYPE=Prestige.NPC") = 1.0
classlevel("TYPE=Prestige.NPC.PC") = 1.0
Corrected example and merged to branch.
sn #19844 & svn 19845
svn #19844 & svn 19845
svn #19844 & svn 19845