### Instruction:
Given a reference text about The Universal Data Element Framework (UDEF), tell me how the framework is used.

### Input:
The Universal Data Element Framework (UDEF) was  a controlled vocabulary developed by The Open Group. It provided a framework for categorizing, naming, and indexing data. It assigned to every item of data a structured alphanumeric tag plus a controlled vocabulary name that describes the meaning of the data. This allowed relating data elements to similar elements defined by other organizations.

UDEF defined a Dewey-decimal like code for each concept. For example, an "employee number" is often used in human resource management. It has a UDEF tag a.5_12.35.8 and a controlled vocabulary description "Employee.PERSON_Employer.Assigned.IDENTIFIER".

UDEF has been superseded by the Open Data Element Framework (O-DEF).

### Response:
The UDEF is a framework for categorizing, naming, and indexing data.