Full Idea
The 'in re' view of structures is that there is no more to structures than the systems that exemplify them.
Clarification
'In re' means 'in the thing' (as opposed to 'ante rem', 'prior to the thing')
Gist of Idea
Is there is no more to structures than the systems that exemplify them?
Source
Stewart Shapiro (Philosophy of Mathematics [1997], 3.3)
Book Reference
Shapiro,Stewart: 'Philosophy of Mathematics:structure and ontology' [OUP 1997], p.85
A Reaction
I say there is more than just the systems, because we can abstract from them to a common structure, but that doesn't commit us to the existence of such a common structure.