Full coverage: The South China Sea Issue
The Philippines wants two rulings from the Arbitral Tribunal: one, that China’s maritime rights in the South China Sea are those that are established by the UN Convention on the Law of the Sea, and two, that China’s Dotted-line claim is invalid.
Manila believes the Nine-Dash Line claim is contrary to the Convention. It also says some maritime features that China has laid claim to are not islands under the Convention, but low-tide elevations and are not capable of generating maritime entitlement.
However, China's foreign ministry says according to international law, the entity that enjoys maritime entitlements is the state that owns the maritime features, rather than the maritime features themselves.
The Convention explicitly grants the maritime entitlements to the "coastal State" of the maritime zones in question.
China says apart from State sovereignty, the first step must be a preliminary decision on who the "coastal State" is. Otherwise discussing legal status is meaningless.
In addition, whether low-tide elevations are subject to occupation is a question of territorial sovereignty. And that's beyond the scope of the UN Convention.