In numerous places in the documentation, a feature is listed or described as "C only." Many of these features are actually available in Ada. For example, in Contour_Plot (plcont in the traditional binding), the transformation from array indices to world coordinates is mentioned as "C only" but is actually available in Ada.
The C documentation for plscmap1l, (Set_Color_Map_1_Piecewise in the thick binding) and plscmap1la (Set_Color_Map_1_Piecewise_And_Alpha in the thick binding) states that if the last argument is a null pointer, the behavior is as though a proper-length array of all False values was passed. In Ada, these procedures are overloaded to allow a last argument that can be either an array of Boolean or a value of the enumerated type (Reverse_Hue_None, Reverse_Hue_All).