1-6.6 Relationship.
The specification of a familial relationship may be important if it is
known. Some other relationships, such as "friend" or "sponsor" may imply that P1 and P2 are
possibly near the same age and/or from the same place. A rule involving these relationships would
be rather imprecise. Rules for most relationships are valid in the case of birth date and place
propagation, but in the case of marriage date and place propagation (in the P-family of P1) it is "self."
