pointer.item

Pointer items are internal file 'placekeepers', which point to the frame where the actual data resides.

Items are normally stored in a file with a few bytes of overhead data, followed by the item-id, followed by the attributes, and then an end-of-item indicator.

If the size of the item exceeds a given length (860 bytes for a 1-k frame system, 1720 bytes for a 2-k frame system), then AP uses a 'pointer item' in the file, which contains the overhead data, the item-id, and a frame address which points to where the attribute values are stored, so most of the item's data will reside outside of the file's primary filespace.

This method increases performance during most Access functions, as reading pointer items is considerably more efficient than reading the entire item during such common functions such as LIST or SORT.

A data file may be delcared (at create-time) to contain all pointer items, forcing every entry to be a pointer item. There is no converse non-pointer item declaration.