The number needs its issuing jurisdiction
A registration number is meaningful only within the system that issued it. Identical digits can occur in different countries or registers, and letter prefixes may distinguish legal forms or registration series. Copy the identifier exactly, including leading zeroes, and identify the issuing authority before searching a document or database that uses a different numbering convention.
Keep tax and global identifiers separate
The UK company search accepts a company number, while Australian ABN Lookup can work with several business search inputs. An EIN has a tax function under the IRS system and should not be substituted for a state company number. When reconciling records, preserve each identifier in a labelled field instead of collapsing all numbers into one supposed international registration code.