Full Idea
For idealists and phenomenalists sense-data are part of physical objects, for objects consist only of actual or actual and possible sense-data; representative realists say they just have an abstract and structural resemblance to objects.
Gist of Idea
For idealists and phenomenalists sense-data are in objects; representative realists say they resemble objects
Source
Howard Robinson (Perception [1994], 1.1)
Book Reference
Robinson,Howard: 'Perception' [Routledge 2001], p.3
A Reaction
He puts Berkeley, Hume and Mill in the first group, and Locke in the second. Russell belongs in the second. The very fact that there can be two such different theories about the location of sense-data rather discredits the whole idea.