Sandstone features fully-typed predicates. Like for all resources, you need to provide a name, which can include a namespace and folders. You then provide the definition of the loot table.
The minimal syntax for predicates is the following:
As you can see, you must provide the
condition of the predicate. Depending on this condition, several properties will be available.
Predicates do not have additional properties, however they have condition-dependant properties. All those can be found directly via autocompletion (as shown above), or by looking at the Minecraft wiki article on Predicates.