ENUMERATED Type in NCL Programming

The ENUMERATED type is used to constrain a component to a defined set of values. Each defined value is named using a name identifier similar to a component name. Associated with each name is a unique integer value (which can be signed), for example:
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The ENUMERATED type is used to constrain a component to a defined set of values. Each defined value is named using a name identifier similar to a component name. Associated with each name is a unique integer value (which can be signed), for example:
Color ::=ENUMERATED { red(0),blue(1),yellow(2),                       green(3),black(7) }
External Form -- Input
The external form must be one of the names listed in the ENUMERATED type. The enumerated values are not allowed (that is, red is valid, 0 is not).
External Form -- Output
Same as input.
Local Form and Behavior
Internally, the ENUMERATED value is kept in the same manner, and is subject to the same local form constraints, as an INTEGER of the binary local form.