Patent ID: 7937652

Claim:
A document processing device, comprising: a storage unit that stores an index, wherein the index associates: a first version of a file with a first annotation through a key; the first annotation with a first position at which the first annotation occurs within the first version of the file; a second version of file with a second annotation through the key; the second annotation with a second position at which the second annotation occurs within the second version of the file; and the first version of the file and the second version of the file through the key; and a processor, the processor functioning as: a change point determination unit that receives the first version of the file and the second version of the file, determines that the second version of the file contains changed information different from information in the first version of the file, and determines a changed position at which the changed information occurs in the first version of the file; an annotation acquisition unit that receives the changed position from the change point determination unit, determines that the changed position is associated with the first position using the index, determines that the first annotation is associated with the changed position using the index, and selects the first annotation based on a result of the determination that the first annotation is associated with the changed position; an additional information modification unit that modifies the character string included in the first annotation to create a modified annotation and stores the modified annotation in the storage unit as the second annotation.