Baltimore Catechism on Schism (note its use of full + partial communion, which rad trads claim is a meaningless Vatican Two novelty, thus savoring of heresy)

 The Baltimore Catechism 

169A. What conditions are necessary in order that a person be a member of the Mystical Body in the full sense?

Inorder that a person be a member of the Mystical Body in the full sense, it is necessary that he be baptized, that he profess the Catholic faith, and that he neither separate himself from the Mystical Body nor be excluded by lawful authority. And if he refuses to hear them, appeal to the Church, but if he refuses to hear even the Church, let him be to thee as the heathen and the publican. (Matthew 18:17)

169B. How does a baptized person separate himself from full incorporation in the Mystical Body?

A baptized person separates himself from full incorporation in the Mystical Body by open and deliberate heresy, apostasy or schism.

169E.When does a baptized person separate himself from full incorporation in the Mystical Body by schism?

A baptized person separates himself from full incorporation in the Mystical Body by schism when he openly refuses obedience to the lawful authorities of the Church, particularly to the Pope.