VERIFY

To read a file from disk to be sure that it can be read is to verify that the
file was written without any errors. When data is written to a disk, there 
is a small chance that it may not be readable later. DOS provides a VERIFY 
switch to let you force it to ALWAYS check that anything written to disk is 
readable. The VERIFY command controls the VERIFY switch. The COPY command 
has a VERIFY option, to verify specific file copies.

Turning VERIFY on will really slow down operation of your computer, so don't 
use it unless you are forced to.
