Q: What is the role of the third author in international publications?

You have not mentioned whether the third author is the last author. The first author is invariably the author who did the maximum amount of work; this holds true irrespective of which field you are from. However, the order of the co-authors varies by field. In some fields, the co-authors are named in alphabetical order, while in other fields, the order of authors depends on the degree to which they have contributed. Thus, the third author would have contributed less than the second author, the fourth author less than the third, and so on.

However, if you are referring to the third author in a three-author paper, things might be different. In this case, the third author would be the last author. The last author in some fields assumes special importance: he or she is usually the supervisor or the PI, the person who has procured grants and under whose supervision the project has seen completion.

You might also find the following articles useful:

• Deciding the order of authors on a paper
• SLIDE DECK: Authorship (Part 2): Deciding the order of authors on your manuscript