On Thu, 17 Aug 2006, David Berry wrote:
> DAT__ROOT and DAT__NOLOC have different notional meanings; one is a
> valid locator to the root of the file system, and the other is an invalid
> locator. Supplied with DAT__NOLOC, ndf_open would report an error, but
> supplied with DAT__ROOT it would function as normal. At the moment,
> ndfPlace cannot distinguish these two cases.
There seems to be a precedent in some system calls (eg mmap using
MAP_FAILED) to allow us to define DAT__ROOT as (HDSLoc*)-1.