[netcdfgroup] Adding create/modify times to _NCProperties?

• To: netCDF Mail List <netcdfgroup@xxxxxxxxxxxxxxxx>
• Subject: [netcdfgroup] Adding create/modify times to _NCProperties?
• From: Dennis Heimbigner <dmh@xxxxxxxx>
• Date: Sun, 13 Dec 2020 21:19:22 -0700

I am considering adding a create time and a last modified time to
the _NCProperties provenance attribute in the netcdf-c library.
Any opinions on this?  Would it be of any use?

=Dennis Heimbigner
Unidata

Details:

1. add two fields to the _NCProperties attribute of the form
   |...,Created=<time>,Modified=<time>|
2. The time is number of microseconds since the start of the Unix epoch
   time.
3. The modtime is an approximation in that it is changed whenever a
   file is closed
   (sync'd actually) and the file was opened for writing. This means
   that if the file
   was opened for writing, but not actually written, the modtime will
   still be changed.
4. There is a cost to re-writing the _NCProperties attribute if the
   modtime is changed.