A discipline is a route taken by a novice when they graduate. They can choose Healing, Alchemy or Warrior Skills and wear the subsequent colour to go with it. Women who wish to choose Warrior Skills are always persuaded otherwise, and so there are no women Warriors, and they are also semi expected to choose Healing, most likely to do with the social culture of the lands. Female Lonmars for example are not allowed to join the Guild due to their culture.
Colours of Robes Based on Discipline:
Those with a black sash are the heads of that discipline, and in the beginning of The Magicians' Guild Lady Vinara is Head of Healing, Lord Sarrin is Head of Alchemy and Lord Balkan is Head of Warrior Skills.