Another one:

 Editor [edt]
    A person, family, or organization contributing to a resource by revising or elucidating the content, e.g., adding an introduction, notes, or other critical matter. An editor may also prepare a resource for production, publication, or distribution. For major revisions, adaptations, etc., that substantially change the nature and content of the original work, resulting in a new work, see author 

Last one, then I leave you alone

 Metadata contact [mdc]
    A person or organization primarily responsible for compiling and maintaining the original description of a metadata set (e.g., geospatial metadata set) 

I agree with @meowcat.

Should I propose a PR to the record format description, proposing the use of [dtc] and [com] if appropriate?

You are welcome to propose a PR for the record format description. But, if I understood it correctly, this will be a change which breaks compatibility. This means it will take some time until its included in all neede places.
With the formal description I can implement it on the codebase. If the code is working I need to convert all existing data to the new format as well. and finally we need to incorporate the changes to RMassBank, which I cant do.

I don't believe this would break compatibility; it would merely explicitely foresee the possibility to allow putting MARC relator tags behind names. Right now, there is actually no specification at all for how the author names should be presented. So maybe this would require a small adaptation in the validator, but otherwise I don't think a change is required...

Do we have a pointer on how R package descriptions do that ?
There is a machine readable
Authors@R: c(person(given = "John Doe", email = "...", role=c("cre"), ...)
and the "compiled" version Author: Jon Doe, Jane Austen, ...
we have in https://github.com/MassBank/RMassBank/blob/master/DESCRIPTION#L5
I'd like to not change our AUTHOR, but add a machine readable (and compile/renderable)
extended version. Yours, Steffen

@meowcat Then I probably misunderstood your proposed extension/changes. Could you please give an example?

@sneumann: I would argue that there is currently no syntax that would be changed, since there is a variety of formats used for the AUTHORS field, with more or less the same info in slightly different iterations:

https://github.com/MassBank/MassBank-data/blob/master/Eawag/EA016651.txt
AUTHORS: Stravs M, Schymanski E, Singer H, Department of Environmental Chemistry, Eawag
https://github.com/MassBank/MassBank-data/blob/master/Fac_Eng_Univ_Tokyo/JP000004.txt
AUTHORS: KOGA M, UNIV. OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH
https://github.com/MassBank/MassBank-data/blob/master/Fiocruz/FIO00009.txt
AUTHORS: Markus Kohlhoff, Natural Product Chemistry Lab (CPqRR/FIOCRUZ, Brazil)
https://github.com/MassBank/MassBank-data/blob/master/Fukuyama_Univ/FU000010.txt
AUTHORS: Matsuura F, Ohta M, Kittaka M, Faculty of Life Science and Biotechnology, Fukuyama University
https://github.com/MassBank/MassBank-data/blob/master/NaToxAq/NA000011.txt
AUTHORS: Tobias Schulze, Hubert Schupke, Martin Krauss, Department of Effect-Directed Analysis, Helmholtz Centre for Environmental Research GmbH - UFZ, Leipzig, Germany
https://github.com/MassBank/MassBank-data/blob/master/MetaboLights/ML001351.txt
AUTHORS: Mark Earll, Stephan Beisken, EMBL-EBI
https://github.com/MassBank/MassBank-data/blob/master/CASMI_2016/SM801802.txt
AUTHORS: Krauss M, Schymanski EL, Weidauer C, Schupke H, UFZ and Eawag
https://github.com/MassBank/MassBank-data/blob/master/Athens_Univ/AU100903.txt
AUTHORS: Nikiforos Alygizakis, Anna Bletsou, Nikolaos Thomaidis, University of Athens
https://github.com/MassBank/MassBank-data/blob/master/UFZ/UA000303.txt
AUTHORS: C. Gallampois (Umea), E. Schymanski (Eawag), W. Brack (UFZ)
https://github.com/MassBank/MassBank-data/blob/master/Washington_State_Univ/BML00009.txt
AUTHORS: Cuthbertson DJ, Johnson SR, Lange BM, Institute of Biological Chemistry, Washington State University
https://github.com/MassBank/MassBank-data/blob/master/Metabolon/MT000006.txt
AUTHORS: Evans A M, Mitchell M, DeHaven C D, Barrett T, Milgram E, Metabolon Inc.
https://github.com/MassBank/MassBank-data/blob/master/MPI_for_Chemical_Ecology/CE000022.txt
AUTHORS: Ales Svatos, Ravi Kumar Maddula, MPI for Chemical Ecology, Jena, Germany
https://github.com/MassBank/MassBank-data/blob/master/ISAS_Dortmund/IA000011.txt
AUTHORS: Nils Hoffmann, Dominik Kopczynski, Bing Peng
https://github.com/MassBank/MassBank-data/blob/master/RIKEN_ReSpect/PM000309.txt
AUTHORS: Parejo I, et al.
https://github.com/MassBank/MassBank-data/blob/master/UPAO/UPA00014.txt
AUTHORS: K.A. Wilkinson & S.N. Miranda

Different order of first and last name, use of brackets, spelling of double initials, use of punctuation, different specifications for the institutes both in format and detail etc. So whatever anyone chooses to put in their AUTHORS doesn't really contradict any existing format or rule. I could go on endless; to my dismay no one is apparently using the semicolon, which I would have wanted since I find it convenient.

My current PR, as a basis for discussion, is mostly a suggestion how people might want to specify authorship, since this would fit in with any scheme people are currently using, and not be more or less machine-readable than before.

I agree that a thought-out new version of AUTHORS (or a substitute) should be machine-readable.

(Ideally we would incorporate ORCID.)

Ah, I found a few more interesting schemes. Including my semicolon! Note that many of these are actually by "us" as in "the people discussing here".

https://github.com/MassBank/MassBank-data/blob/master/CASMI_2012/SMI00021.txt
AUTHORS: S. Neumann: IPB-Halle, Germany & E. Schymanski: Eawag, Switzerland
https://github.com/MassBank/MassBank-data/blob/master/Literature_Specs/LIT00014.txt
AUTHORS: E. Schymanski; retrieved from M. Castillo et al. 2000
https://github.com/MassBank/MassBank-data/blob/master/Boise_State_Univ/BSU00003.txt
AUTHORS: Chandler, C. and Habig, J. Boise State University
https://github.com/MassBank/MassBank-data/blob/master/BS/BS001003.txt
AUTHORS: Plant Biology, The Noble Foundation, Ardmore, OK, US/Dennis Fine, Daniel Wherritt, and Lloyd Sumner Institute first, and even a slash!

This is not meant to criticise any of the formats that were used, only pointing out the complete absence of anything systematic, even among high-quality and involved contributors.

Yes I totally agree its's a good time to start using some conventions; @MaliRemorker and I were discussing how to write the author statement for the hopefully soon-to-be-coming LCSB records, he's looking into your suggestions our side. I agree with @sneumann that we should retain a plain text AUTHOR field (but add some recommendations for use into the documentation to avoid this in the future) and add a machine readable one as an extra, to retain backwards compatibility and ease-of-use for users.
We would then have to decide with @meier-rene whether we standardize this information in already-existing records - at least the plain text field?

ORCIDs ... maybe a separate field?