what's the datasets used in flink sql document?

[??????]

Could anyone tell me 
what's the datasets used in flink sql document?


For sql like:
val revenue = orders   .filter($"cCountry" === "FRANCE")   .groupBy($"cID", 
$"cName")   .select($"cID", $"cName", $"revenue".sum AS "revSum")
Thanks for your help