You don't differentiate in method interface between internal tables and other variable types. There is no equivalent in a method to a function's TABLES interface. Instead, the parameter type should be a reference to a table type.
In my opinion, this is best done by defining the table type in the Dictionary. If you've not done this before, go to SE11, select radio button Data type, enter the type name and click create. When prompted choose table type. Essentially a Dictionary table type is a definition of an internal table that can be used in ABAP logic.
Alternatively, you can also define table types locally within your class, however such types can only be used privately, not in the interface of a public method.
Scott
