In its opposition to the government's motion for a protective order in United States of America v. Donald J. Trump, Waltine Nauta, and Carlos De Oliveira, Waltine Nauta's defense refers to Donald Trump as the "lead defendant". I'm wondering whether this is a precisely defined legal term. The term is apparently in common use, including in official government communication (e.g. here, here, here), but I can't find a definition for it anywhere.
The Wikipedia article on Obergefell v. Hodges says "Wymyslo was substituted as the lead defendant, and the case was restyled Obergefell v. Wymyslo", but none of the documents in the references for that statement contain the term "lead defendant". The statement seems to indicate that the lead defendant is the first one in the list of defendants, whose name is used for the case style. If so, does this have any legal relevance beyond the style?
In the original indictment and the superseding indictment, Walt Nauta and Carlos De Oliveira are referred to as "Trump's co-conspirators", whereas Trump himself is never referred to as a "co-conspirator". That might suggest that Trump is alleged to be something like the "lead conspirator", but the conspiracy statute makes no distinctions among the conspirators.
So my impression is that "lead defendant" is just an informal term for the defendant whose name appears first in the list of defendants, and that this carries no legal implications. Is that correct?