ICAO FPL item numbering

[fcit]

Was wondering whether anybody would have a clue, why there is gaps in the numbering of items on the ICAO flight plan, i.e. it starts with Item 3 (message type) than Item 7 (a/c ident) and so forth - how about Item 4-6?

I would imagine that the numbering has an historical background. Anybody could shed some light in the dark?

Thanks
fcit

[Icarus]

Item numbers on the form are not consecutive, as they correspond to Field Type
numbers in ATS messages.

http://canfltbrf.ec.gc.ca/navcan/flight/flight_plan/InstructionsE.pdf

[fcit]

Thanks Ikarus,

well, so they correspond to ATS Field Type designators. And where could I find a description of those?

brgds
fcit

[Icarus]

Appendix 3 of ICAO Document PANS-RAC 4444.

[fcit]

Brilliant tip,
thanks a million mate. Don't have a copy of Doc 4444 right at hand, so it took me a while to access one over the net, but this is exactly what I was looking for!!!

Thanks
fcit