A computer product including a data structure for organizing of a plurality of documents, and capable of being utilized by a processor for manipulating data of the data structure and capable of displaying selected data on a display unit. The data structure includes a plurality of directionally interlinked nodes, each node being associated with one or more documents having a header and body text. All the documents are associated with a given node and have identical normalized body text. All documents that have identical normalized body text are associated with the same node. One or more of the nodes is associated with more than one document. For any node that is a descendent of another node, the normalized body text of each document associated with the node is inclusive of the normalized body text of a document that is associated with the other node.