[NEST Users] Writing gdf files in binary format

Hello, I am trying to write spikedector data into .gdf files in binary format, but I cannot. I am setting the 'binary' param of the spikedetector to True (I checked it using nest.GetStatus) but files are written in ASCII. Do I need some special python package? I am using python 2.7.5 and NEST 2.18. Thanks in advance. Xavier Computer Vision Center<http://www.cvc.uab.cat> CONFIDENTIALITY WARNING<http://www.cvc.uab.es/?page_id=7475>