It seems that last week's demonstrations (no strike) weren't enough to find an agreement.
This call to strike is "renewable", which means that anybody can go on strike anytime from the 12th onward. No time limit. As far as I know, more than 400 calls nationwide.
On the ATC side of the problem, my prediction is : huge disruption the 12th (beginning the 11th after 1700 UTC). Then, once again, the daily disruptions due, once again, to the minimum service (as explained above).