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7.3.28 LiteralNull


   A literal null specifies the lack of a value.



    LiteralSpecification (from Kernel ) on page 93


   A literal null is used to represent null (i.e., the absence of a value).


   No additional attributes


   No additional associations


   No additional constraints

   [1] The query isComputable() is redefined to be true.

   LiteralNull ::isComputable(): Boolean;isComputable = true

   [2] The query isNull() returns true.

   LiteralNull ::isNull() : Boolean;isNull = true


   LiteralNull is intended to be used to explicitly model the lack of a value.


   Notation for LiteralNull varies depending on where it is used. It often appears as the word ‘null.’ Other notations are described for specific uses.