This question is not really about who can be considered a coauthor of a given journal paper —or maybe it is, after all— but rather about how to specify the different roles, levels of implication or contributions of each of the coauthors, in case this would mean to be done.
My question is: Is there any standard about how to specify the different roles or contributions of the coauthors of a given journal paper? I do not mean the importance of coauthors that can maybe deduced from their order in the author list (see What does first authorship really mean?, Authorship allocation - is it common to grant equal credit to two last authors?, for instance), but a way to explicitly specify the implication of each of the coauthors, in a sort of standard way.
I remember someone saying this could be added at the end of each article, as a way to make the contribution of each coauthor clearer.
Actually, my question is highly related to this previous one: Revamping Paper Authorship, *or* Should Papers Roll Credits, which has only received one answer and is still open at the moment of writing.
I have found some interesting webpages and articles dealing with this subject:
So, maybe my question is actually about the state of the art of this subject: how to credit authorship in a standard way or standard authorship crediting.
Other related questions in this site: