Info within the Flight ID

[Bethsalem]

Does the letter or letters at the end of a flight ID give information regarding the type of flight?

What I mean by that is say you see "MON518M" on screen.  Does the "M" at the end mean that this Monarch flight is not carrying passengers but is heading to an airport for maintenance?

Likewise, if I see "TOM3725P", does the "P" mean that the flight is again not carrying passangers, but is positioning out to pick them up to fly another route? 

Do other letters have any significance regarding the nature of the flight?

[tarbat]

Whilst it doesn't really answer your question, there's some useful information about Flight IDs at http://en.wikipedia.org/wiki/Airline_codes#Call_signs_.28Flight_identification_or_flight_ID.29

EDIT:  Looks like it's up to each airline how they construct their callsigns.  See discussion at http://www.pprune.org/spectators-balcony-spotters-corner/367295-flight-number-suffixes.html

[DaveReid]

Not much to add to Tarbat's response.  It's still common for (M)aintenance, (T)raining and (P)ositioning flights to use the appropriate suffixes, but with the advent of "callsign confusion" countermeasures you will also see those letters (and others) used as suffixes or in alphanumeric combinations designed to eliminate the possibility of confusing, say, BAW123 with AFR123.

[Bethsalem]

Thanks to both of you for replying.  The pprune forum link was helpful.