Figure style

[heidivanparys]

Comment in response to https://www.ogc.org/standards/requests/246:

The style of the figures is different in the section on Conventions and in the other sections, which is confusing.

The same line and arrowhead styles should be used, and the style should be the one from the UML spec. Preferably, the same colours should be used.

[jyutzler]

I'm really struggling here. I was having a hard time rendering my PlantUML at all and temporarily switched to Mermaid. One of the downsides to that is the solid triangles in inheritance/realization.

I now have PlantUML working again and so I have fixed those graphical issues. However, the Conventions section uses inline PlantUML and for some reason that UML is rendered in a theme that is no longer published with the latest version. This is better but not perfect. See 765c881.

Argh free software!

[heidivanparys]

It is possible to get an EA license via OGC, perhaps in a future revision, that should be used to do the UML? See also the material from the Conceptual Modeling session at the TC meeting Madrid.

[jyutzler]

It would be possible to remove the inline notation and replace it with new implementations.

I have opened the notion of EA-diagrams as #635. Either way, the inline diagrams would have to be replaced.