You cannot use the RALTER command to change the data type of a custom field. Instead, you must delete the CFIELD profile using the RDELETE command and then redefine it with the RDEFINE command. If you have already assigned field values to any users or groups, the data type for those custom fields will not change because the TYPE is stored in the RACF® database with the custom field data. The new TYPE for the custom field will be reflected when subsequent CSDATA values are assigned using the new custom field with the updated TYPE.

For example, you might have a user custom field called PHONE defined with TYPE(NUM) that you want to change to a TYPE(CHAR) field. If you already used the PHONE keyword to define phone numbers for three user profiles, those PHONE values are stored in the RACF database as integer values. After you change the definition of the PHONE custom field to TYPE(CHAR), the three integer values remain, while subsequent phone numbers will be stored in the RACF database as character fields. This might confuse users who list these values because numeric fields and character fields are displayed differently.