Hi, the concept of ports, attached to the outside bounds of an element allowing connections between elements is a widespread concept. Adding this concept would help generic layouting algorithms taking ports into account (such as KIELER) doing a much better job. Since DI defines abstract subclasses, meta models without ports can simply choose to not use the concept.

The spec currently has no constraint sections. Should we add them? For
example, we might require unowned diagram elements to be diagrams

All the Associations in DC/DG/DI have names except just one:

<packagedElement xmi:type="uml:Association" xmi:id="A_style_canvas" memberEnd="Canvas-packagedStyle A_style_canvas-canvas">
<ownedEnd xmi:type="uml:Property" xmi:id="A_style_canvas-canvas" name="canvas" type="Canvas" association="A_style_canvas"/>
</packagedElement>

Is this intended?

There is a small typo in the DD specification document.
On page 17 we can read:
"namely the Diagram Graphics(DI) package (Clause 9) and the Diagram Interchange(DG) package"

The acronyms in the parenthesis are reversed, it should be Diagram Graphics(DG) and Diagram Interchange(DI).

There are some typos in the attributes description of Color data type, we can read:
"Integer [1] - the red component of the color in the range (0..255)"
for all three components, green and blue included.

The description should reflect the correct color.

The final Association in DG.xmi

<packagedElement xmi:type="uml:Association" xmi:id="A_style_canvas" memberEnd="Canvas-packagedStyle A_style_canvas-canvas">
<ownedEnd xmi:type="uml:Property" xmi:id="A_style_canvas-canvas" name="canvas" type="Canvas" association="A_style_canvas"/>
</packagedElement>

has no name. This is at best poor practice and contrary to the guidance at the end of UML 2.5 2.4.2.

DD 1.0 defines DI, DC, DG as Models which is not in the CMOF subset for MOF 2.4.1

This is a change to the DD XMI to replace Models with Packages. There is no change to the primary specification.
Disposition: Resolved

The description of the Canvas element does not say how attributes inherited from GraphicalElement are handled. Since the Canvas explicitly references a background color and a fill, I assume that the attributes "sharedStyle" and "localStyle" are only taken into account for calculation of an effective style of child elements. Since the canvas defines a background, I guess it should fill the parent UI control, so a clip path wouldn't make much sense. Since transforms can also be applied to the fill of an application, I guess the transforms are just applied to the group of containing children. Please clarify, if this assumptions are correct.

Since canvases are groups, they inherit the fact that "The (local or shared) styles defined on a group cascade to its member elements" (see Subclause 10.3.12), that is, the styles are not for the group itself (the revision below spells out the meaing of "cascade"). Conversely, canvases support background colors and fills for themselves (backgroundColor and backgroundFill), as opposed to their members.
Graphical elements, including canvases, can have clip paths applied to them to restrict painting (for example, applying an oval mask to a background). This is separate from the fact that canvases, as groups, are lower in z-order than their members and therefore appear to be additionally clipped by their members.
Fills can have transforms (Fill::transform) to change how they are applied on their graphical elements. This is separate from transforms on graphical elements (GraphicalElement:transform), which apply to graphical elements themselves.

In the standard the description of MarkedElement states "It is an abstract super class of all graphical elements whose vertices are explicitly specified and ordered.". However the heading declares "[Class]", which is inconsistent with the naming of other classes. The heading should declare it "[Abstract Class]". And in the CMOF files the MarkedElement is not modeled as an abstract class.

Revise as suggested

Diagram Common should reuse MOF Primitive Types

Remove DD primitive types and import UML PrimitiveTypes into DC

A DG library for BNF parsing would enable language-specific DI's capture strings, instead of modeling BNF constraints.

Yes, but it would not be a DG library. It would be provided by the mapping language used between DI and DG, which is it is not defined by DD.
Disposition: Closed No Change

Section 8.1.3 (Z-Order) should be specific to the ownership association on DiagramElement to itself, and should be moved to DI and DG.

This is merged with 16909, which addresses the same topic.
Disposition: Duplicate/Merged

In Figure 9.2 (Diagram Element) DiagramElement ownership should be ordered and given occlusion semantics, per Section 8.1.3 (Z-Order).

Add ordering to DI::DiagramElement::/ownedElement ordered. Move Clause 8.1.3 (Z-Order) to the description of DiagramElement::/ownedElement, modified for diagram elements, and also to DG::Group::member, modified to diagram graphics

The definition of DiagramElement has an association to the depicted MOF Element with a multiplicity of [0..1]; so, one DiagramElement can represent at most one model Element. However, UML contains at least one notation in which a single symbol represents more than one Element: using a single State symbol to represent multiple similar States (see p.601 of the UML 2.4 Superstructure Specification). Will DD be able to support this notation?

Loosen multiplicity of DiagramElement::/modelElement property to *. Also resolves 16907 by using UML::Element instead of CMOF::Element in the Diagram Interchange metamodel

Is a DG library needed to calculate bounding boxes for strings in particular fonts?

No, would be provided by the mapping language used between DI and DG, which is it is not defined by DD.
Disposition: Closed No Change

Diagram elements might have multiple modelElements (for example, state lists in UML state machines, combined merge/decision diamonds in UML activities). Languages can specialize to 1 or order as needed.

This duplicates 16628.
Disposition: Duplicate/Merged

In Figure A.1 (UML DI Metamodel), the multiplicities opposite UMLLabel should be 0..1.

Revise as suggested.

DD should use the latest formal version of CMOF

See resolution of 16628.
Disposition: Merge/Duplicate