1. A computer readable medium storing a program causing a computer to execute a process for document processing, the process comprising: receiving image data obtained by, with an image reading apparatus, reading a document of a predetermined format in which contents of an electronic document stored in a storage portion while being associated with identification information, the identification information, and an entry for additional information are arranged; extracting entered additional information from the entry area of the received image data; and correlating the extracted additional information with an electronic document associated with the identification information.