Hatha-Vinyasa (Gokul) Yoga is a complete system that brings an intense and deep Asana practice united to a specific alignment based on bandhas and "marmas".
Gokula is the name of a very blessed place on the Yamuna river, a Sacred river for the Vaishnavas.
This system was compiled by Maha Yogi Gokulacandra Das, as the name says, a great yogi of our times, and the system carries his name as a tribute to its origins.