Co-authored-by: Remi Gau <[email protected]>

- Change primary rules from dot points to enumerations, and reference rules by number where applicable.
- Move from subsequent text into this list rules relating to improper placement of metadata files within the directory structure, and not permitting multiple applicable files at one level of the hierarchy.
- Add "corollaries" section incorporating text relating to interpretation and consequences of the rules, separating them from subsequent examples.

As the inheritance principle makes reference to tabular files and JSON key-value dictionaries, but there are no such references in the opposite direction, these files should be defined prior to introduction of the Inheritance Principle.

Having a metadata file applicable to multiple data files can occur not only at one level of the directory hierarchy, but additionally to many data files at lower levels of the hierarchy.

Resolves bids-standard#946 with bids-standard#962.

Co-authored-by: Yaroslav Halchenko <[email protected]>

Co-authored-by: Stefan Appelhoff <[email protected]>

The rule regarding the fact that it is not possible to "unset" a key-value pair from a JSON file from higher in the filesystem hierarchy is here moved to the "corollaries" section. This is because this behaviour is a natural consequence of loading consecutive JSON files using a simple merge operation, and the absence of an equivalent to Python' "None" in the JSON specification.

…ng_corollary

Conflicts:
	src/02-common-principles.md

Inheritance principle: No unsetting as corollary

…lues

Co-authored-by: Stefan Appelhoff <[email protected]>

Co-authored-by: Stefan Appelhoff <[email protected]>