15. A system according to claim 13 , wherein the first semantic representation of the first data content comprises a first semantic digest defining a plurality of entity types and one or more instances of each of the plurality of entity types which are within the first data content, and wherein the third semantic representation comprises a third semantic digest of a third plurality of entity types and one or more instances of each of the third plurality of entity types which are within the first data content or the second data content.
15. A system according to claim 13 , wherein the first semantic representation of the first data content comprises a first semantic digest defining a plurality of entity types and one or more instances of each of the plurality of entity types which are within the first data content, and wherein the third semantic representation comprises a third semantic digest of a third plurality of entity types and one or more instances of each of the third plurality of entity types which are within the first data content or the second data content. 16. A system according to claim 15 , wherein the first semantic digest is a first resource definition framework graph, wherein the second semantic representation comprises a second resource definition framework graph of a second plurality of entity types and one or more instances of each of the second plurality of entity types which are within the second data content, wherein the third semantic digest is a third resource definition framework graph, and wherein generation of the third semantic representation comprises program code executable by a device to perform a Union operation between the first resource definition framework graph and the second resource definition framework graph.