SYSML2_ — Update language description and concrete syntax related to imports

The resolutions by the KerML FTF to the following issues make restrictions to the functionality of imports in KerML and hence, by reference, in SysML, also:

• KERML_-73 Disallow public imports at root level
• KERML_-74 Make imports private by default
• KERML_-75 Restrict the functionality of recursive import

The discussion of imports in Clause 7 Language Description need to be updated to reflect these changes (particularly in 7.5.3 Imports). In addition, adopting the requirement to always show visibility of imports in the concrete syntax, consistent with KERML_-74, requires changes in

• 8.2.2.5.1 Packages (textual notation)
• 8.2.3.5 Namespaces and Packages Graphical Notation
• 8.3.5 Namespaces and Packages Abstract Syntax, Figure 5 Namespaces

Update language description and concrete syntax

Agreed that the appropriate subclauses need to be updated, similarly to the updates made to corresponding subclauses in the KerML Specification by the resolutions to each of the stated issues. Note, however, that the resolution allows the VisibilityIndicator to be optional on the graphical notation for import relationships, even though it is mandatory on the textual notation (consistent with the resolution of KERML_-74). This is consistent with the common practice of allowing information to be elided in the graphical notation in order to permit more tailored diagrammatic presentation of portions of a model.