The whole of rules on information codification (linguistic, contextual, gestural…) agreed on for the annotation of a resource, such that a given event is represented in a consistent and unambiguous way. It allows for the interoperability of annotations done by different operators, at different times. There are conventions developed within projects (ex. PFC, Rhapsodie, LANGACROSS, CLAPI…), and laboratories (ex. DELIC/GARS).