Canon Degree.

Canon degree, also know as the Germanic system, is based on early German modes of determining kinship categories and organizing relationships. It is associated with a system of counting kinship distances by using the joints that extend from the top of the head to the tips of the fingers. The system is of both contemporary as well as historical importance, since it is enshrined in British common law and was used in Catholic canon statutes prior to the Vatican II reforms.

The canon degree system assigns kinship on the sole basis of the larger of the number of links that either Ego or Alter can count back to their most recent common ancestor.

The number determining canon degree is calculated as the larger of the number of links that either Ego or Alter can trace back to his/her most recent common ancestor.
In this case,

Ego counts 4 links,
Alter counts 3 links,
the canon degree is 4, the greater of the two numbers.

Canon degree numbers are applied to specific relationships as follows:

While the canon degree measure may seem less intuitively obvious than that of the civil system, it incorporates several features that are particularly appropriate to traditional European social organization. Firstly it places all nuclear family members in the same category, that of first order or primary kin, reflecting the salience of this inner social circle in Western traditions. Secondly, beyond this range, it maps out a nested series of stocks or bilateral descent groups stemming from Ego's ancestors at various degrees of removal and extending to relatives within Ego's own generation. Stocks have been recorded as significant social units in Celtic and Germanic Europe.