The daily track message has a line for any special routeing to track.
See EUR RTS WEST NIL in todays:
(NAT-2/2 TRACKS FLS 310/390 INCLUSIVEAPR 25/1130Z TO APR 25/1900Z
PART TWO OF TWO PARTS-
D DINIM 51/20 51/30 50/40 49/50 JOOPY
EAST LVLS NIL
WEST LVLS 310 320 330 340 350 360 370 380 390
EUR RTS WEST NIL
NAR -
E SOMAX 50/20 50/30 49/40 48/50 NICSO
EAST LVLS NIL
WEST LVLS 310 320 330 350 360 370 390
EUR RTS WEST NIL
From the latest
NORTH ATLANTIC OPERATIONS AND AIRSPACE MANUAL
The NERS valid for a particular day will be published in the NAT Track Message but will only be published when the traffic density warrants their use. They are not expected to be published every day. Full details of all NER routings together with associated procedures are published in
CFMU Route Availability Document Annex NAT:
Very good link here as to how the whole routeing is put together
http://occ.ivao.aero/index.php?site=pilots