16. A document management and exchange system comprising: one or more computer systems including: a descriptor adding unit to add a descriptor to an original document for exchange between two or more participant computer systems along a communication path, wherein the descriptor comprises at least one document identifier representing a logical subject of the document; a modification identifying unit to identify in further documents received from the communication path at the two or more participant computer systems modifications with respect to the original document based on comparing a descriptor of the further documents and the descriptor of the original document, wherein the further documents represent modified versions of the original document exchanged between the two or more participant computer systems, and wherein at least one participant computer system receives a further document with modifications different than modifications in another further document received by at least one other participant computer system; and a master document maintaining unit to maintain a master document for each of the participant computer systems containing the original document and the modifications in the further documents received by that participant computer system from the communication path during the exchange of the modified versions of the original document between the two or more participant computer systems, wherein the master document for each participant computer system provides consolidated information relating to the logical subject and the modifications received by that participant computer system, and wherein the master documents for at least two of the participant computer systems are different and include different modifications based on the further documents received at those at least two participant computer systems.
16. A document management and exchange system comprising: one or more computer systems including: a descriptor adding unit to add a descriptor to an original document for exchange between two or more participant computer systems along a communication path, wherein the descriptor comprises at least one document identifier representing a logical subject of the document; a modification identifying unit to identify in further documents received from the communication path at the two or more participant computer systems modifications with respect to the original document based on comparing a descriptor of the further documents and the descriptor of the original document, wherein the further documents represent modified versions of the original document exchanged between the two or more participant computer systems, and wherein at least one participant computer system receives a further document with modifications different than modifications in another further document received by at least one other participant computer system; and a master document maintaining unit to maintain a master document for each of the participant computer systems containing the original document and the modifications in the further documents received by that participant computer system from the communication path during the exchange of the modified versions of the original document between the two or more participant computer systems, wherein the master document for each participant computer system provides consolidated information relating to the logical subject and the modifications received by that participant computer system, and wherein the master documents for at least two of the participant computer systems are different and include different modifications based on the further documents received at those at least two participant computer systems. 23. The system according to claim 16 , further comprising: a control unit to control access to the master document based on a data access matrix for each participant, the matrix including access authorization information of the participants to master documents and being based on the descriptors of the master documents and a distribution list.