A relator (a cover term) is a °flag or a °subordinator.
The term "relator" (as discussed by Dik 1983) is not widely used in the literature, but it does seem to be useful, so it is included here. For example, Jackendoff (1977: 78) treats adverbial subordinators ("subordinating conjunctions") such as English because as prepositions, and there are many other languages where adverbial subordinators are adposition-like or formally identical to adpositions (Kortmann 1997: 58-69).