Express a typed relationship between two sequences.

For example, this could be used to describe an orthology (in which case attribute ‘type’ is ‘orthology’).

:Parameters:

id_ref_0 : Id
    first sequence reference identifier
id_ref_1 : Id
    second sequence reference identifier
distance : float
    distance between the two sequences
type : restricted string
    describe the type of relationship
confidence : Confidence
    confidence value for this relation