In recent consultations with the Austrian transport ministry, we were discussing the possibility of relaxing the requirement to use bike facilities. The draft amendment to the rules of the road (StVO: Straßenverkehrsordnung) would have allowed local roads authorities to define nonmandatory bike paths in individual cases, using the signs shown in the first picture.
We had our doubts about whether these signs were consistent with international practice, and so I did a bit of research. You can see the results in Signs for nonmandatory bike paths (PDF). It turned out that the Austrian signs would (once again) have departed from the pattern already in use in a plurality of countries. The idea is presumably based on the existing Austrian sign for a pedestrian zone.
As of the present, nothing has come of the proposals, since the whole idea of exceptions to the requirement to use bike facilities was categorically rejected by the other half of the ruling coalition, the conservative Volkspartei (the current transport minister is a Social Democrat; and since she has just introduced a helmet law for children we’re not exactly happy with her either).