Is it possible to split a NOTAM in two messages in case it is too long to fit in a single message?
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
  Q) YMMM/QOBCE/IV/M/AE/000/999/3357S15111E008
  A) YSSY PART 1 OF 3
  B) 1811190334 
  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.