Item restrictions
Item restrictions are an optional feature you can use to specify valid or invalid data objects for an item type. Item restrictions are grouped into three categories: Value, Character, and Range.
Restrictions of an item type are the valid or invalid values for that item. "Include" restrictions are all of the valid values for an item. "Exclude" restrictions specify all of the invalid values.For example, a unit of measure field in the data must be one of a set of values: CN, BX, PK, BR. These values should be defined as "include" restrictions of the item UnitOfMeasure.
Defining restrictions for an item restricts the valid data for that item. Partial lists of the valid values are not possible. For example, it is not possible to define the values for a certain item to be {A, B, C, "some other possible values"}.
While you can define restrictions for any item, most items will not have restrictions. For example, you would not want to restrict the valid values of a name field because you would probably want to accept any name as valid data for that field. However, you could assign restrictions to it if needed.