cf50a5b8_GPlates_Data_Manual_Table_3__Properties_Table_Used_In
[Property] subductingSlab [Optionality] Optional, required for dynamic polygon closure [Description] Indicates the side of the plate boundary of the subducting slab (the slab that is being subducted into the mantle). Takes a value of "Left", "Right", or "Unknown". Note that in this context, "left" specifically refers to the left hand side from the perspective of an observer travelling through the geometry of the object. This means "left" is entirely dependent on the order in which the points that comprise the geometry of the plate boundary were digitised. That is to say, if the plate boundary was digitised with the first point being in the South, and the last point being to the North, then the "left" is the plate to the West. If on the other hand, the exact same plate boundary were digitised with the first point being in the North, and the last point in the South, then the "left" plate is to the East. See diagram below. image::leftRight.png [Used In] 
SubductionZone
GPlates Data Manual
Used In