SYSML2_ — Inconsistent use of guillemets in graphical notation for metamodel aspects

The graphical notation makes use of enclosing guillemets to mark up presentation of the metaclass as well as possible metaproperties and metamodel extensions of a model element (i.e., their mapping to the SysML abstract syntax or metamodel). However, there are inconsistencies in their application. The following graphical BNF productions are affected:

• -name-compartment productions,
• -edge and -relationship productions,
• productions including user-defined keywords that extend the metamodel.

Currently, metaproperties of a metaclass are treated in different ways. E.g. in a -name-compartment the isAbstract metaproperty is presented as a leading '«abstract»' literal with its own guillemets, while the isReference metaproperty is included in the main metaclass presentation, e.g., '«ref part»'.

A single, consistent rule should be established for all graphical BNF productions that concern presentation of metamodel information.

Inconsistent use of guillemets in graphical notation for metamodel aspects

The proposal establishes a consistent textual rendering in the graphical BNF for meta-properties, consistent with the "prefix" keywords (e.g., for "abstract", "variant", etc.) used in the textual BNF for definitions and usages. The proposal is to group all such meta-property keywords before the "kind" keyword in a single part of guillemets. (The one exception to this the «parallel» keyword, which is not a "prefix" keyword in the textual notation, but appears immediately before the body of a state, indicating that it is the nested substates that are actually running in parallel.)

In some cases, this may lead to longer, multi-word texts between the opening '«' and closing '»'. Such longer texts may need to be wrapped in order to fit within the boundaries of a graphical symbol. This is considered acceptable. Taking into account support for resizing, auto-layout and dynamically reacting views, the graphical notation should not prescribe wrapping nor fixed newlines in the rendering of the meta-properties.