We were told about this the other week when we sold our apartment.
Apparently all addresses in Fethiye are now registered and given a number.
You need this number to renew Dask amongst other things.
They are going around ( haven't got very far yet ) putting little plaques beside the doors with numbers on them.
Our address had actually changed!
we were in Sok 543 but it changed to 545 under the new registration system!
Once you get your number you need to keep a note of it.
We didn't actually have it before we renewed the Dask but they were able to find it on a system somewhere!