Ex rel.
（重定向自Ex relatione）
Ex rel. is an abbreviation of the Latin phrase "ex relatio" (meaning "[arising] out of the relation/narration [of the relator]" ). The term is a legal phrase; the legal citation guide, the Bluebook, describes ex rel. as a "procedural phrase" and requires using it to abbreviate "on the relation of," "for the use of," "on behalf of," and similar expressions.