Full Idea
Formalist Structuralism endorses structural methodology in mathematics, but rejects semantic and metaphysical problems as either meaningless, or purely formal, or as inference relations.
Gist of Idea
Formalist Structuralism says the ontology is vacuous, or formal, or inference relations
Source
E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §3)
A Reaction
[very compressed] I find the third option fairly congenial, certainly in preference to rather platonist accounts of structuralism. One still needs to distinguish the mathematical from the non-mathematical in the inference relations.