Countries can freely decide where to liberalize on a sector-by-sector basis, including which specific mode of supply they want to cover for a given sector.
Mode 4 (Presence of Natural Persons) has the lowest depth of commitments, probably due to a number of sensitivities involved with the movement of foreign workers.
Beginning in February 2012, 50 countries (28 of which are represented by the European Union) around the world began negotiating the Trade in Services Agreement (TISA).
TISA negotiations primarily comprised high- and upper-middle income countries who were members of the WTO and hoped to further liberalize trade in financial services, healthcare, and transportation between themselves.
The agreement has not progressed since early 2016 due to uncertainty surrounding negotiations in the aftermath of many elections that occurred that year.