add 'modality' to glossary

[CPernet]

I've seen the word 'modality' used in different context, for instance /anat and /func defined as 2 (MRI) modalities. Within BIDS, these are not since under 'Modality specific files', what is listed is different data types based on technology.

Proposal: a modality corresponds to a technology-driven data type (MRI, MEG, EEG, Behaviour, Eye tracking, etc) and does not separate within modality (e.g. anat vs. func).

[tsalo]

"anat" and "func" are, I believe, datatypes, rather than modalities. We have a modalities.yaml within the schema that lists the modalities in BIDS.

In #593, we have discussed renaming "modality" to something like "technology" or "instrument".

In #1048, I have proposed adding a new schema file that describes the other files in the schema, including "modalities". This would automatically add these terms to the glossary.

There have been discussions about adding common principles to the schema (e.g., here), which would also include "modality".

[CPernet]

ah of course @robertoostenveld was on the case :-)

Having browsed the different items mentioned above, I do see an issue with name inconsistency I do like your proposal 593 with instruments and data types +1

The spec tree would therefore organize along those two names, with data types as top-level folders for data. What happens to the word modality after that?

[robertoostenveld]

You may want to have a look at some of my notes that relate to this, see my BIDS bigger picture google doc. It aims to clarify instruments, modalities and suffixes.

[CPernet]

I did :-) and instrument/data type sounds good to me (still not defining what modality would be after that)

[yarikoptic]

we have two "types" of modality (term and "entity") listed in Glossary already:

• https://bids-specification.readthedocs.io/en/stable/glossary.html#modality-common_principles

so this issue is IMHO is resolved. For more discussion on possible future changes relating to modality, see e.g.

• Change modality directories to entity format bids-2-devel#55