If you’re working with a VAM 1.22 file and see an error or reference to a “missing or invalid key,” it often indicates:
Keys released for version 1.21 are also compatible with version 1.22. vam 1.22 key
It looks like you’re asking for a text explanation or analysis regarding — likely in the context of Vicon motion capture data or a related biomechanics / animation file format. If you’re working with a VAM 1