Currently, a user may retrieve a delimited list of cancelled OCLC control numbers from the OCLC Control Number (035z) attribute under Bibliographic Details. However, this field has limited usefulness for a couple reasons. First, the field has a limit of 256 characters, which means when a bibliographic record shows more than 15 or 16 OCLC numbers have been merged, some numbers are excluded. Second, and more importantly, each individual control number cannot be matched to other cancelled or active control numbers in other records without being split to a separate field first. This is not a straightforward task in analytics to find and match duplicate record numbers.

It would improve retrieval if there were new field that related each 035z entry to an MMS ID, such that each entry could be retrieved as a separate row in analytics results, and also could be matched as a single identifier to other 035z and 035a data. This field should be similar to the "OCLC Control Number single (035a)" attribute under the Bibliographic IDs dimension.