This variable determines whether or not Vision indexed file data blocks (as opposed to key blocks) will be held in the memory-resident disk buffers. When it is set to 1 (on, true, yes), the default, both data blocks and key blocks will use the buffers. When set to 0 (off, false, no), only key blocks will use the buffers. Setting this value to 1 will usually improve performance unless very few buffers are being used.

Note: Holding data blocks in the buffers slightly increases the chances of losing data if a file opened for MASS_UPDATE is not closed properly (such as a power failure). The default setting of this variable is 1.