Surplus Sectors
This term is used in WinHex in the following way:
Surplus sectors on a logical drive are those few sectors at the end
that do not add to a full cluster and thus cannot be used by the OS
(and thus by no conventional application program either). Synonym:
volume slack.
Surplus sectors on a physical disk are those sectors at the end that
are located outside the regular disk geometry scheme (because they
do not add to a full cylinder/header/track entity), which is why they
are usually not used by any partition or the operating system (or any
conventional application program). Synonym: unpartitionable space.
Surplus sectors have nothing to do with "bad" or damaged sectors or
sectors a hard disk internally uses as a replacement for sectors found
to be faulty.