Ditamap metadata in book title page - what can be done

Hello,

I would want to populate the book title page with ditamap metadata.

variables can be uses in such a scenario but it is not documented.

What I found so far:

Metadata                                    Variable name

author                                          Author

prodinfo/prodname                     BM_ProdName

prodinfo/vrmlist/vrm/@version  BM_Vrm1

Have you complementary information about this

Thanks in advance
Philippe