Would it be in accordance with ICAO norms to issue two different NOTAMs with the same year, series and number regarding the same subject and informing //PART 1 OF 2 PARTS// and //PART 2 OF 2 PARTS// in the NOTAMs bodies to inform that they are parts of a single NOTAM?
Multi-part NOTAMs seem to be part of ICAO standard, as far as googling reveals. I can’t seem to find a definitive reference though.
An example - and from experience a relatively reliable one - for a multi-part NOTAM is the infamous Sydney crane list, at time of writing in NOTAM H6002/18, which at the moment comes in three parts and has the part listing in field A):
H6002/18 NOTAMR H5974/18
A) YSSY PART 1 OF 3
C) 1811300500 EST
E) OBSTACLE CRANES AT FLW LOCATIONS
239FT AMSL BRG 002 MAG 1.58NM FM ARP
497FT AMSL BRG 002 MAG 3.82NM FM ARP
220FT AMSL BRG 002 MAG 1.38NM FM ARP OBST UNLIT
413FT AMSL BRG 003 MAG 3.09NM FM ARP
410FT AMSL BRG 003 MAG 3.14NM FM ARP
577FT AMSL BRG 003 MAG 4.65NM FM ARP
685FT AMSL BRG 004 MAG 4.26NM FM ARP
249FT AMSL BRG 004 MAG 2.98NM FM ARP
413FT AMSL BRG 004 MAG 3.18NM FM ARP
224FT AMSL BRG 005 MAG 1.53NM FM ARP OBST UNLIT
500FT AMSL BRG 005 MAG 3.42NM FM ARP
953FT AMSL BRG 005 MAG 5.26NM FM ARP
623FT AMSL BRG 006 MAG 4.54NM FM ARP
PART 1 OF 3
Found at FAA pilot briefing site.