Pointer authentication instructions in the ARM Foundation Platform

I'm trying to understand the behavior of pointer authentication instructions using the ARM Foundation Platform. I'm confused that Foundation Platform is allegedly configured with both implementation-defined and QARMA5 algorithms (because ID_AA64ISAR_EL1=13112111) despite the fact the ARM ARM says these are exclusive options.

Have I misunderstood? If not, can you state what algorithm is supported and whether this is configurable in any way?

Thanks.