UMLR — Stereotyped Constraints in UML

The UML 2.2 spec (ptc/2008-05-05) does not allow showing only a constraint name in braces. I have found this non-standard feature very valuable when working with business users and would like to see it allowed.

The most flexible way to use constraints is to have a short, informal English description as the name, and real OCL as the formal expression. Having the flexibility to show either the name or the expression gives the best of two worlds: business SMEs can read and validate the informal English name while tools can use the OCL expression to actually enforce the constraints. In addition, a diagram can present a view for business SMEs or a view for technical people.

I recommend changing the notation from this:

<constraint> ::= '

'

to this:

<constraint> ::= '

'

This change would allow:

the author to choose to show:
only { : expression } for technical users (a common practice)
only

for non-technical users (a currently disallowed but important practice)
both

the viewer to tell the difference between the name and the expression when only one is shown
consistency with the way several other things work in UML, such as:
action names
action pin names
instance specification names (i.e., just shows the name when there's no type)

attributes (i.e., one can suppress the ": Type")