The art of improvisation in Āsana functions
through two core practice principles, namely
that of the modification in and of the Āsana
and that of the variation in and of the Āsana.
Each can be defined more specifically in that:
Modification is that which brings you closer to
the Lakṣaṇa or core characteristics of an Āsana.
Variation is that which can take you away from
the Lakṣaṇa or core characteristics of an Āsana.