Linking to another document in the same project

[72757373656c6c]

My question is similar to another asked, except my question is within the same project.

The project structure snippet:

project/source/todo.md
project/source/documentation/guidelines.md

Inside todo.md, I want to reference a header anchor in guidelines.md (guidelines.md#comments).

The variations below produce the desired html for the linked document.

Inline:
- [test1](documentation/guidelines.md#comments)
- [test2](/documentation/guidelines.md#comments)
- [test3](./documentation/guidelines.md#comments)
- test4 <project:./documentation/guidelines.md#comments>

Footnotes:
[^comment1]:[](documentation/guidelines.md#comments)
[^comment2]:[](/documentation/guidelines.md#comments)
[^comment3]:[](./documentation/guidelines.md#comments)

Questions:

1. Is there a way to eliminate the ".md" and just use basename --suffix=.md (guidelines)?
2. Does <project:...> syntax do something different than [](target) format?

Documentation:

• Cross Reference
• Footnotes

Thanks.