Given the following passage  "Presbyterians distinguish themselves from other denominations by doctrine, institutional organization (or "church order") and worship; often using a "Book of Order" to regulate common practice and order. The origins of the Presbyterian churches are in Calvinism. Many branches of Presbyterianism are remnants of previous splits from larger groups. Some of the splits have been due to doctrinal controversy, while some have been caused by disagreement concerning the degree to which those ordained to church office should be required to agree with the Westminster Confession of Faith, which historically serves as an important confessional document – second only to the Bible, yet directing particularities in the standardization and translation of the Bible – in Presbyterian churches.",  answer the following question. Note that the answer is present within the text.  Question: What is controversial between branches?
A:
the degree to which those ordained to church office should be required to agree with the Westminster Confession of Faith