+ @param options (dict)
+
+ As of 3.1.16, the PL driver implements here an important option named
+ 'pltags' that affects the management of slice tags.
+
+ This option can take 3 values
+ (*) options['pltags'] == 'ignore' (default)
+ This is the recommended mode; in this mode all slice tags passed
+ here are ignore, which correspond to the <planetlab:attribute> XML tags in
+ the <sliver_type> areas of incoming rspec to Allocate.
+ In other words you are guaranteed to leave slice tags alone.
+ (*) options['pltags'] == 'append'
+ All incoming slice tags are added to corresponding slivers,
+ unless an exact match can be found in the PLC db
+ (*) options['pltags'] == 'sync'
+ The historical mode, that attempts to leave the PLC db in a state
+ in sync with the ones specified in incoming rspec.
+
+ See also http://svn.planet-lab.org/wiki/SFASliceTags
+