In Analytics within the Subject Area "Usage Date" the "Book DOI" (Counter R4 Reports) or "DOI" (Counter R5 Reports) are not selectable as Title Identifiers.

The same is true for "Proprietary Identifier" (Counter R4) or "Proprietary_ID" (Counter R5).

Since this information is sometimes listed in the corresponding columns of the COUNTER Book reports, it would be helpful if this information could also be retrieved in Analytics.