There are different levels of blocking. The aircraft type as per Stefan's post and your attachment, BLOCKED and completely hidden depending on the source.
This explains it abit further in detail
http://www.radarspotters.eu/forum/in...p?topic=7712.0
I'm guessing FR and FlightAware are using different rules on how to process the information. FR has stated in their Forums they will follow the BARR list and will not explain it in their FAQ.
Not that is really makes much difference if you are willing to pay for a commercial product.
CASA ADSB requirements will be a long process, but they will have a similar BARR list requirement, hence the Police choppers flying over my house every night not showing.
Dec 2013: All operations at and above FL290
Feb 2014: Aircraft operated under the IFR first registered in Australia after 6 Feb 2014. Feb 2016: In large parts of Western Australia (Airspace classes A, B, C and E).
(This is co-incident with the mandatory requirement to fit GNSS to all IFR aircraft for navigation in Australian airspace.)
Feb 2017: All IFR operations at all flight levels
Soon it will be mostly Commerical Aircraft as everyone will just opt-out, they don't need to specify a security concern anymore.