K÷ln, Erzbisch÷fliche Di÷zesan- und Dombibliothek 127, fol. 9r

Gratian, Decretum

D.4 dictum after c.3:   Ordinances are instituted when they are promulgated;  they are confirmed when they have been approved by the usage of those who observe them (Leges instituuntur, cum promulgantur, firmantur, cum moribus utentium approbantur).

D.12 c.6:  Long standing usages approved by the consent of those following them are like ordinances (Diuturni mores consensu utentium approbati legem imitantur).