AS-11 X3:

MXF Program Contribution – HD Long GOP (25p, 50p)

This is a Specification in the AS-11 family of Specifications.  It defines an MXF file format for the delivery of finished HD programs to UK Digital Production Partnership (DPP) broadcasters.

See the specification - Full Specification on GitHub 

At present, there is no Certification program set up for this specification.