Does TP-VML consider to cover also modeling constraints and guidance? Having these set in its metamodel would allow creating only syntactically “legal” models. Examples of such constraints are mandatory values, uniquenesss, legal kind of connections between elements etc.
TP-VML is meant as a graphical equivalent of the Task Planning model (or you might think of it as a meta-model, which is also correct). The TP model is defined here.
At the moment, the TP-VML document uses a set of draw.io elements which are not semantic, i.e. they don’t know about the meta-model. However the Better ArchetypeDesigner does, and it has a visual mode, based on the TP (meta-)model.
Things are still moving both at the TP level and also at the level of graphical representation. If you are thinking of supporting it in a tool, please let us know your ideas and needs.