-either ``IMPLICIT`` (using ``impl`` keyword argument), or
-``EXPLICIT`` one (using ``expl`` keyword argument). Both arguments take
-raw binary string, containing that tag. You can **not** set implicit and
-explicit tags simultaneously.
+either ``IMPLICIT`` (using either ``impl`` keyword argument or ``impl``
+class attribute), or ``EXPLICIT`` one (using either ``expl`` keyword
+argument or ``expl`` class attribute). Both arguments take raw binary
+string, containing that tag. You can **not** set implicit and explicit
+tags simultaneously.