Many entities that have entries in the Registers are defined both by AAF and MXF – and the two formats normally provide slightly different definitions (at the least the
Name are typically different). In general, if an entity is defined in AAF then the Registers entry is based on the AAF definition.
However, there are some Elements that are mandatory in AAF but optional in MXF. In these cases the approach has generally been to mark these Elements as “optional” where they appear in the Groups Register.
Specific exceptions related to AAF/MXF implementation (and differences between the formats) are covered elsewhere – read the documentation thoroughly before beginning any implementation using the Registers.