Hi Noor,

PPM capabilities for Project, Program and Portfolio Management have been built mostly around best practices described in PMP/PMI PMBoK. We've seen implementations of multiple methodologies with PPM, such as PMP/PMI, Prince2, or Stage Gate Process, to name a few. So far we haven't chased any official certification for the PPM product, since many of the "fine-grained" specific requirements needed by each customer will be implemented by partners or professional services during the product configuration phase. 

Moreover, it seems like ISO 21500 is a document describing concepts in the context of providing some guidance on following good practices, and doesn't seem to be a standard that's a good fit for an official certification process.

Thank you for the reply. 

Your response matches the response from our PS partner. We delivered that to the customer and they are happy :) 

Thanks again!