(Optional; PDF 1.4) A subsidiary image XObject defining a soft-mask image to be used as a source of mask shape or mask opacity values in the transparent imaging model. The alpha source parameter in the graphics state determines whether the mask values are interpreted as shape or opacity. If present, this entry overrides the current soft mask in the graphics state, as well as the image’s Mask entry, if any. (However, the other transparency related graphics state parameters — blend mode and alpha constant — remain in effect.) If SMask is absent, the image has no associated soft mask (although the current soft mask in the graphics state may still apply).

public const string SMask

Public Const SMask As String

public:
literal String^ SMask