How can a user identify the name of a field from a custom field ID?

[Nancy Bonanno]

So if user #1 creates and shares a filter using custom field IDs, like cf[21102], how does user #2 know which field is being referred to?  How does he figure out that is really "International Tax Code" or whatever the name is?  

Thanks for any help.

[Nic Brough -Adaptavist-]

No. Your licence is for one server at 500 users.

Atlassian are looking at site licences and will be introducing a 250 user licence level soon (I'm not sure what "soon" is though - I'd guess sometime between Summit and Christmas), but at the moment, you can't do this.