> IMO it should goes like that:
> - Each duplication of a road should duplicate restrictions.
> - Any modification of access flags for original or duplicated roads
> should be performed accordingly on restrictions.
> - Redundant restrictions should be removed, this can happen because of
> changes in access flags or when restriction goes wrong-way.

Yes, that's what it should do.

>
> > Assume that a via way of an only_left restriction has
> > also an opposite cycleway. Should mkgmap create
> > all possible combinations of restrictions to make sure that
> > also bicycles are only routed left ?
>
> I don't understand this problem. If OSM restriction "only_left_turn"
> include bicycle, then you should create Garmin restrictions to route
> bicycles too.

correct. As I said in my next post, I forgot that the mapper can
specify to which vehicles the restriction applies.
My fear is that I can have multiple arcs for each part (from,via,to) of a restriction relation.
If the restriction applies to cars and bicycles and all arcs allow traffic for both of them,
I have to add various combinations of arcs.
I don't know if this happens, I assume that style developpers are NOT
creating duplicate arcs which allow the same vehicles.
The make-opposite-cycleways option adds a cycleway and
forbids traffic for bicycles on the normal road.
I think I should be able to create a reasonable amount of restriction for that.

>
> I see your next post, will processing of restriction:bicycle solve this
> question?

Yes, this  and the except=* tag. I just have to add code to support
type=restriction:* tags.

Gerd