Issue 9700: UML's support for null values and semantics is unclear (uml2-rtf)
Source: Adaptive (Mr. Pete Rivett, pete.rivett(at)adaptive.com)
Nature: Uncategorized Issue
Severity: 
Summary: UML's support for null values and semantics is unclear. 
For example if a Property is defined [1..1] then is a value of null (represented by LiteralNull) permitted? (LiteralNull is defined as "LiteralNull is intended to be used to explicitly model the lack of a value.")
Can null values be used to create a sparse array? If not how is a fixed length sparse array to be modeled?
Can a unique multivalued property contain multiple nulls?
How do the StructuralFeatureActions react in the presence of null?
[Note that the issue is NOT related to the "null token"]

Resolution: 
Revised Text: 
Actions taken:
May 4, 2006: received issue
Discussion: 

End of Annotations:=====
ubject: Issues on UML 2.1 ptc/06-04-02
Date: Wed, 3 May 2006 21:47:55 -0700
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Thread-Topic: Issues on UML 2.1 ptc/06-04-02
thread-index: AcZvNehepr/4NO0dQeiR1bghcnVDzg==
From: "Pete Rivett" <pete.rivett@adaptive.com>
To: <issues@omg.org>
Cc: "Bran Selic" <bselic@ca.ibm.com>


(These arose from discussions with the UML group from DMTF)
 
1) UML's support for null values and semantics is unclear. 
For example if a Property is defined [1..1] then is a value of null (represented by LiteralNull) permitted? (LiteralNull is defined as "LiteralNull is intended to be used to explicitly model the lack of a value.")
Can null values be used to create a sparse array? If not how is a fixed length sparse array to be modeled?
Can a unique multivalued property contain multiple nulls?
How do the StructuralFeatureActions react in the presence of null?
[Note that the issue is NOT related to the "null token"]