Confusing Explanation for Figure 29

[egekorkan]

Above Figure 29 there is the following text:

In this figure the WoT building blocks are highlighted with black outlines. The WoT Thing Description is a key building block that provides metadata describing a Thing and its network interface. Security, a cross-cutting concern, is separated into public and protected private components. The WoT Scripting API is optional and the Binding Templates are informative. The WoT Discovery building block defines mechanisms for distributing Thing Descriptions; a Thing can provide Thing Descriptions directly, or they can be provided by a Thing Description Directory service.

This text is quite confusing and mixes building blocks with the specification normativeness. It says highlighted in black outlines but are dotted ones also building blocks? It seems that the initial intention was to say that the dotted ones are informative blocks but Discovery is not. I would not bother making such a difference since whether a block is informative or not does not change this general architecture.
We can talk whether a block is optional for an implementation or not but in that case binding templates are not really optional, each td has binding template vocabulary one way or another. Each Thing has private security data as well (unless nosec).

Also, what does the arrow between Thing and TDD imply?

Also, this figure does not have profiles.

Figure 29 for easy reference:

[egekorkan]

Also there are disrepencany between this and the following figures:

• https://w3c.github.io/wot-architecture/#arch-webthing (regarding contents of td)
• https://w3c.github.io/wot-architecture/#architecture-implementation (regarding servient vs thing)