COMPRESSION/DECOMPRESSION OF TAGS IN MARKUP DOCUMENTS

In a tag document compressing/decompressing technique, a tag document compressing apparatus, for example, has a tag extracting unit for scanning document type definition of an inputted tag document to extract a tag, a tag code table creating unit for assigning a predetermined code to the tag in the document type definition on the basis of the tag extracted by the tag extracting unit to create a tag code table, and a tag coding unit for coding the tag in document instance on the basis of the tag code table created by the tag code table creating unit so as to compress the document in consideration of the tag in the tag document, thereby improving a compression rate of the tag document and decreasing a quantity of data of the same.