There is no mask file available for this SRTM file.  This generally indicates that no significant voids were filled in, or interpolated within this file.  For further information on the void filling methodology, see:

	 http://srtm.csi.cgiar.org/SRTMdataProcessingMethodology.asp

For further information on the CGIAR-CSI SRTM 90m Database, see:

	http://srtm.csi.cgiar.org/