SYSML11 — Section: 8.3.2.1

1) The definition of Constraint [5] for Block in section 8.3.2.2 is defined as "The following constraint under section [...] in the UML Superstructure Specification is removed by SysML: [...]". 2) The UML 2.1.2 Superstructure Specification states in section 18.1.2 under 'Extensibility': "It is not possible to take away any of the constraints that apply to a metamodel such as UML using a profile, [...]". 3) In Section 6 of the SysML-Specification, it is stated that "The SysML specification is defined by using UML 2 specification techniques. These techniques are used to achieve the following goals in the specification. Correctness [...] The specification technique used in this specification describes SysML as a UML extension that is defined using stereotypes and model libraries." The points 1), 2) and 3) together are a contradiction.

The referenced text from the introductory section of Chapter 6 is incorrect.
SysML is defined using not only stereotypes and model libraries, but additional
techniques including diagram extensions as well as the removal of a specific
existing UML constraint, as noted by the issue. The initial statement that "The
SysML specification is defined by using UML 2 specification techniques" is
incorrect since some of these extension techniques are not provided by UML 2.
The second statement that "These techniques are used to achieve the following
goals in the specification" is incorrect since the specification techniques used are
not sufficient to achieve the listed goals. Remove this introductory section entirely
to avoid misleading statements and to eliminate the contradition noted by the
issue.