Dublin Core element for accession number?

Hello, I'm a relatively archivist (since January of this year) creating an archive for a community organization. We are getting ready to install Omeka Classic, and I have been trying to create a cross-walk for our present ad-hoc management system (which is basically an excel sheet) to easily import everything into Omeka when the time comes. I've managed to work out pretty much everything, but am stuck on finding a Dublin Core element or term appropriate for an accession number because "identifier" is already taken by the item's identifier number, which is different from the accession number. For those who use DC, do you have accession numbers? Any advice would be appreciated. Thank you in advance for your time!