Core doctrine and Adiaphora - What's the difference?

http://www.storiesoffaith.ca/inplenary/2007/02/core_doctrine_and_adiaphora_wh.html

[The General Synod of he Anglican Church of Canada] 19 June 2007--In answer to the question put to it by General Synod 2004, the Primate’s Theological Commission (PTC) concluded that “that the blessing of committed same-sex unions is a matter of doctrine,” but “not a matter of what is often referred to as a ‘core’ doctrine, in the sense of being credal doctrine.”

Now, I readily admit that the PTC’s conclusion is not especially profound, and I can understand why some are not pleased with it. After all, it does not clearly satisfy anyone’s prejudices.[i] But before I comment further on the categories of doctrine discussed in the St. Michael Report (SMR), let me suggest that this should be one reason why the report ought to be commended to the church. While the SMR doesn’t develop a theology of sexuality or sexual ethics, it does lay out what we think needs to be talked and prayed about in the hope that the church will be helped to overcome the supercharged rhetoric that divides us.