SysML1.0 10.3.2.1 ConstraintBlock:

'All properties of a constraint block are constraint parameters, with the exception  of constraint properties that hold internally nested usages of other constraint blocks.'

SysML1.0 8.3.2.2 Block

'. SysML establishes three standard classifications of properties belonging to a SysML Block. A property typed by  a SysML Block that has composite aggregation is classifed as a part property. A property typed by a Block that does not have composite aggregation is classified as a reference property. A property typed by a UML DataType or SysML ValueType is classified as a value property.' 

Some examples of the MD SysML ConstraintParameter (including some provocative ones outside SysML).

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