When developing in FileMaker, your default option for key values is FileMaker's auto-enter serial numbers. While this option can use an alphanumeric value instead of strict serial numbers, the general consensus for these documented standards is to use a universally unique identifier (UUID). Using a UUID scheme for creating keys nearly eliminates the chance of creating duplicate keys, which is a common problem when migrating data to new files (and remembering to reset auto-enter serial numbers) and when merging data created on multiple devices.
It is suggested that a wrapper custom function be used when integrating UUID values. A wrapper function is simply a Custom Function with a unique name which points to another chunk of code, internal or external function - see method stub. The suggested standard name for this reserved function is UniqueID.
In FileMaker, UUIDs are generated one of three ways: FileMaker's Get ( UUID ) function, plug-ins, or custom functions. Any one of the following or some other method may be referenced within the UniqueID custom function.
Get ( UUID )