20. A computer comprising: a storage media to store a first instance of a modular document, wherein the modular document is composed of plural component documents relating to respective different content of the modular document, where the different content are combined to allow presentation of the modular document; a processor to: receive a second instance of the modular document; access merge definitions contained in respective ones of the first instance and the second instance of the modular document, wherein each of the merge definitions provides information regarding how conflicts in the first and second instances are to be resolved; resolve a conflict between the merge definitions in the first and second instances to produce an output merge definition; and use the output merge definition to resolve any conflicts between the first instance and the second instance of the modular document.
20. A computer comprising: a storage media to store a first instance of a modular document, wherein the modular document is composed of plural component documents relating to respective different content of the modular document, where the different content are combined to allow presentation of the modular document; a processor to: receive a second instance of the modular document; access merge definitions contained in respective ones of the first instance and the second instance of the modular document, wherein each of the merge definitions provides information regarding how conflicts in the first and second instances are to be resolved; resolve a conflict between the merge definitions in the first and second instances to produce an output merge definition; and use the output merge definition to resolve any conflicts between the first instance and the second instance of the modular document. 24. The computer of claim 20 , wherein the processor is configured to further present, to a user, any conflict between the first and second instances of the modular document not resolved by the output merge definition.