https://www.epo.org/en/service-support/faq/law-practice/unitary-patent/register-unitary-patent-protection/there-any
Is there any specific code in the Register for unitary patent protection or in the European Patent Bulletin?
Unitary Patents are assigned a specific identifier (the identifier "C0") in the Register for unitary patent protection, the European Patent Bulletin and in the data sets provided by the EPO, making it easier to identify them through the EPO's patent information products and services, e.g. Espacenet and Global Patent Index.