db:ignore-driver-privileges: should v shall (ODF all versions)

Dear all,

----
The defined values for the db:ignore-driver-privileges attribute are:

 * false: privileges returned by a database driver should not be
ignored.

 * true: privileges returned by a database driver should be ignored.
----

The effect of using "should" here is that these behaviours are only
recommendations. Should not "shall" be used instead? -- otherwise there
is no guarantee that a document processor will honour the value here,
which could be important in some environments, I suspect.

- Alex.