[Tagging] bicycle=use_sidepath applicable to bicycle lanes?

[Joachim]

Use_sidepath was invented to solve the *routing* problem of compulsory
*separate* cycle paths. Usage of use_sidepath together with
highway=*+cycleway=* was hotly discussed after the proposal got
accepted.[1]

The question is: Are there somewhere on this world non-compulsory
cycle lanes (cycleway=lane)? If yes, we have two possibilities:

1. use_sidepath/-lane
First use_sidelane has to invented for cycleway=lane.
Afterwards it's technically not difficult to define: "A highway with
bicycle=use_sidepath/-lane and with tag cycleway=track/lane does mean
the track/lane is compulsory". But this looks odd.
Also very important is :lanes tagging, which is the advanced way of
tagging a cycle lane:
bicycle:lanes=use_sidelane|use_sidelane|designated looks good and
allows using one lane for turning.

2. bicycle:obligatory[2]
The obligatory suffix proposal is by me. A highway with
cycleway=track/lane and cycleway:bicycle:obligatory=yes looks very
natural.
Lanes tagging looks also good: bicycle:obligatory:lanes=||yes.



[1] http://wiki.openstreetmap.org/wiki/Talk:Tag:bicycle%3Duse_sidepath#bicycle.3Duse_sidepath_only_if_the_cycleway_is_a_separate_highway_.28like_highway.3Dcycleway.29
[2] https://wiki.openstreetmap.org/wiki/Proposed_features/Obligatory_access_suffix#Rationale