The Crystal Cathedral

In the Canon law of the Catholic Church the relationship of the bishop to his cathedral is often compared to the relationship of a pastor to the parochial church. Both are pastors over an area (the diocese for the bishop and the parish for the pastor) and both are rectors over a building (the cathedral for the bishop and the parish church for the pastor). In view of this, canon lawyers often extend the metaphor and speak of the cathedral church as the one church of the diocese, and all others are deemed chapels in their relation to it.
Cathedral churches may have different degrees of dignity:
1. A parish church which was formerly a cathedral is known as a "proto-cathedral".
2. A parish church temporarily serving as the cathedral or co-cathedral of a diocese is known as a "pro-cathedral".