I would question whether it was correct to change section 11.3.1.1 "Activity" by replacing the BDD representation of activity hierarchy (as per v1.3) with adjunct action properties (introduced in v1.4). Whilst the latter is possible with the AdjunctProperty facility, the prior method, inherited from UML, is still valid. That is, unless the UML activity hierarchy is expressly deprecated from SysML. Even then, it will leave end users with the question of what the additional benefit is of the adjunct property as applied to call behaviour actions.

Closed, no change: Restrict bdd presentation of activities

There is no need that SysML restricts the modeling of activities in block definition diagrams like it is allowed by UML rules. The paragraph above Figure 11-1 in 11.3.1.1.1 says "Properties with AdjunctProperty applied ... can be used", it doesn't say they must be used.

It seems that the SysML specification wants to exclude the usage of qualified associations. However, it only says that it does not seem to be essential to use them:

"Qualified associations, shown in SysML by an open box at the end of an association path with a property name inside, are a specialized feature of UML that specifies how a property value can represent an identifier of an associated target. This capability, while useful for data modeling, does not seem essential to accomplish any of the SysML requirements for
support of systems engineering." (8.3.1.3, SysML 1.5)

It is still unclear if qualified associations are allowed or not.

Explicitly exclude the usage of qualified associations

Qualified associations are explicitly excluded by the second sentence in clause 8.3.1.3: "Notational and metamodel support for n-ary associations and qualified associations has been excluded from SysML.".

The SysML specification excludes the usage of association arrowheads:

"The use of navigation arrowheads on an association has been simplified by excluding the case of arrowheads on both ends, and requiring that such an association always be shown without arrowheads on either end." (8.3.1.3, SysML 1.5).

However, arrowheads are commonly used in SysML modeling. There are also examples of usages in the SysML specification itself, for example, figure D.15.

Association arrowheads at both ends at the same time are forbidden

The specification only excludes the case of arrowheads at both ends of an association at the same time. The modeling scenarios mentioned by the reporter are still possible in SysML.