Job question

[Niwashi]

Also worth noting is that cross class skills that aren't part of your job's class set (Main Class/Sub Class) are super useful, and you'll have one or two additional "sub classes" that you can get skills from.

For example, White Mage has Conjurer as its primary class and Arcanist as its sub class, but they can also get skills from Thaumaturge and Archer.

The way I understood it is that it's exactly one other class (in addition to the job's required secondary class). A White Mage can pull from Arcanist or Thaumaturge, but not Archer.

The primary class has to be at least level 30 to unlock the job, it shares the same level and XP as the job, and all its class skills are available to the job (as normal skills — not cross-class).
The secondary class has to be at least level 15 to unlock the job, and it's available to pull cross-class skills from.
The tertiary class isn't required, but can be used to pull cross-class skills from in the same way as the secondary class.

Warrior: Marauder (primary) + Gladiator (secondary) + Pugilist (tertiary)
Paladin: Gladiator (primary) + Conjurer (secondary) + Marauder (tertiary)
Monk: Pugilist (primary) + Lancer (secondary) + Marauder (tertiary)
Dragoon: Lancer (primary) + Marauder (secondary) + Pugilist (tertiary)
Bard: Archer (primary) + Pugilist (secondary) + Lancer (tertiary)
White Mage: Conjurer (primary) + Arcanist (secondary) + Thaumaturge (tertiary)
Black Mage: Thaumaturge (primary) + Archer (secondary) + Arcanist (tertiary)
Summoner: Arcanist (primary) + Thaumaturge (secondary) + Archer (tertiary)
Scholar: Arcanist (primary) + Conjurer (secondary) + Thaumaturge (tertiary)