value statement

The statement <LABEL> value <VALUE TYPE> is used to identify <VALUE TYPE> as the value type of the <LABEL> attribute type.

<VALUE TYPE> should be a built-in or a user-defined value type.

Schema for the following examples 
#!test[schema]
define attribute name @abstract;

Defining attribute type’s value types

The value keyword can be used to define a value type of an attribute type.

#!test[schema]
define name value string;

Undefining attribute type’s value type

The value keyword can be used to undefine an attribute type’s value type.

#!test[schema]
undefine value string from name;

Matching

The value keyword can be used to match all attribute types with a value type.

#!test[read]
match $a value string;