Is their alternate for api user to map custom fields instead of name and id?

[shiva]

I want know is there an alternate for api users to map custom fields instead of name and id.

[Nic Brough -Adaptavist-]

How would that work?  Given that the id of a custom field is the unique identifier in the database (and the name a human proxy which could be duplicated, but usually won't be)

What else would you use to map a custom field?