"Kentb" <> wrote ...
> Is tagging then not a function of Explorer and the directory file, but
> rather
> the file being tagged? ie, the tagging information is kept in the file
> that
> is tagged and thus becomes application specific?
No :-)
Exposing file properties in Explorer is the job of a "Shell Extension" -
basically a DLL supplied by the 3rd party vendor which gets installed into
Explorer. So for example, Adobe install a "PDF Shell Extension", usually
C:\program files\common files\adobe\acrobat\activex\pdfshell.dll - which
enables the Properties for PDF files, in Explorer.
How the extension determines and stores the various Properties, is entirely
up to the logic and ingenuiyty of the programmer writing the extension. Some
properties, such as File Size, can be easily determined by standard
operating system calls - so there's no need to store them separately. Other
custom properties, such as "Author" or "Should this document be reviewed?"
are often stored as Alternative File Streams in the File object. So, they
are not kept "in the file" in any obvious kind of way; they are metadata
associated with the default data stream of the file. See
http://msdn2.microsoft.com/En-US/library/aa969349.aspx
and
http://msdn2.microsoft.com/en-us/library/aa969360.aspx
for the grisly details!
Cheers
Andrew