| 摘要 |
PURPOSE:To allow the system to cope with a record definition change by providing a physically arranged sequential pointer, a display sequential pointer and a new item definition pointer among item cells and also a bit map representing the existence of the item in a record. CONSTITUTION:A record definition body consists of a file cell 1 and an item cell 2 and the physical structure of the record is formed with a bit map length section 3, a bit map section 4, and a date item 5. The physically sequential pointer is shown in solid lines and the display sequential pointer is shown in dotted lines, and in adding a data item 5-4 to a data item 5-3, the value of the bit map length section 3 is set to 4 so as to form the bit map section 4 in 4-bits and the presence up to the item 5-4 is represented by writing ''1'' to all and an item cell 2-4 is connected by a pointer. To delete the item 5-2, 0 is written in a location representing the item 5-2 of the bit map section 4 and the pointer is to be replaced. |
