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# Custom Field ID Format

Going forward, all new Custom Fields will share a common ID prefix, `cf_`,
instead of object type specific prefixes like `lcf_` for Lead Custom Fields, and
`ccf_` for Contact Custom Fields.

Existing Custom Field IDs will not change, but be advised that we will soon
allow existing Custom Fields to become Shared Custom Fields. This means a Shared
Custom Field may have an ID prefix previously reserved for another object type.
The ID prefix should not be used to infer the type of object associated with the
Custom Field.