The only meta-data on a Participant included the SMP data-model is its identifier. Based on this identifier the capabilities can be queried and as the SMP provides no further information on the Participant itself no other data is needed. For administration purposes Holodeck SMP adds a name and contact info to the Participant meta-data. 

To manage the Participants and their capabilities in the administration UI click on Participants in the top-level menu bar.
As explained on the page about Service Meta-data Templates you don’t need to create the Service Metadata for each Participant individually but simply bind the applicable Service Metadata Template to the Participant. 

When the SMP server is registered in the Peppol SML the Participant can also be registered in the SML by checking the Register in SML? check-box.

Service Meta-data Templates