What to populate for Underlying identification for CDS?

ESMA provides some guidance on how to populate the underlying identification for CDS.

Question:

Paragraph 248 of the guidance says “field ‘Underlying identification’ should be reported in case of Credit Default Swap (CDS) based on specific reference obligation. For CDS hedging against the default of an entity, such entity should be reported in the ‘Reference entity’ field”, (emphasis added)

Could you clarify if this is to be interpreted as meaning that for a single name CDS:
• field 2.144 (Reference Entity) is to be populated (with either country code, country code plus subdivision code, or LEI), and
• field 2.13 (Underlying identification type) will be left blank.

Answer: 

It depends, if the single name CDS references a specific obligation (e.g. a single bond of an issuer), the identifier of that obligation should be provided. If the CDS protects agains any default of that issuer (not linked to a specific bond), the ID of the issuer should be provided.

For multiname CDS (typically index CDS),  generally we would expect the identifier of the reference obligation