symbol

Shared symbol placement (Apple GridLayerPaint.symbol); defaults sync from icon.placement.

Declared last on purpose. grid and sample occupy positions 6 and 7 in every SDK version through 1.6.0, so inserting this parameter ahead of them would re-bind the 6th and 7th positional argument of GridLayerPaint(...) and copy(...) — a change a caller that passes positional arguments cannot see, because GridPaint and SamplePaint? would simply fail to match and the error names the wrong parameter. Appended, every 1.6.0 call site keeps its meaning.