1. A method of displaying digital document data with partial text data therein replaced with mask data, the method comprising: acquiring, on a computer, digital document data; accepting, on the computer, a selection of an instance of partial text data to be replaced, the partial text data located within the digital document data; generating, on the computer, replacement document data that comprises a copy of the digital document data in which the instance of the partial text data is replaced with an identification information uniquely associated with said instance of the partial text data; storing, by the computer, a replaced document data, which comprises the replacement document data and an identification of a region of the replacement document data that includes the identification information corresponding to the instance of the partial text data, wherein the replacement document data comprises more than one region; accepting selection of one of a plurality of rule information pieces, which comprises a replacement information that associates the identification information with a mask pattern; and replacing, based on the replacement information, the identification information of the instance of the partial text data included in the replaced document data with the mask pattern.
1. A method of displaying digital document data with partial text data therein replaced with mask data, the method comprising: acquiring, on a computer, digital document data; accepting, on the computer, a selection of an instance of partial text data to be replaced, the partial text data located within the digital document data; generating, on the computer, replacement document data that comprises a copy of the digital document data in which the instance of the partial text data is replaced with an identification information uniquely associated with said instance of the partial text data; storing, by the computer, a replaced document data, which comprises the replacement document data and an identification of a region of the replacement document data that includes the identification information corresponding to the instance of the partial text data, wherein the replacement document data comprises more than one region; accepting selection of one of a plurality of rule information pieces, which comprises a replacement information that associates the identification information with a mask pattern; and replacing, based on the replacement information, the identification information of the instance of the partial text data included in the replaced document data with the mask pattern. 4. The method according to claim 1 , further comprising storing an association between the instance of the partial text data and the identification information.