There are many different numbering schemes for assigning numbers to entities. These generally require an agreed set of rules, or a central coordinator.
Numbering schemes include:
The E.164 numbering plan for telephone numbers, including:
... failure[?]
Acyl-CoA dehydrogenase, medium chain, deficiency of[?]
Acyl-CoA dehydrogenase, short chain, deficiency of[?]
Acyl-CoA dehydrogenase, very long chain, ...