| 摘要 |
PROBLEM TO BE SOLVED: To erase a document file under limitation conditions such as the number of accesses, access time and moving frequency without being influenced by the environment of a computer. SOLUTION: A document file consists of a document file management mechanism 301 and a document 302 united with the mechanism 301. The mechanism 301 has a set information table 303 for describing an erasing condition previously set before being entered into a computer, a variable table 304 for setting variable information, an information temporary storage table 305 for storing temporary information necessary for judgment, a directory confirming part 306 for confirming a directory, a timer 307, an information judging part 308 for executing the writing of data in the table, judgment whether a document file coincides with a condition or not, a file erasing part 309 for erasing a document, and a document output part 310 for giving an instructing to output a difference document.
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