EVO Bible
Part II - Resource Descriptions

The flët resource

A flet resource definies the paramaters for a fleet, which is a collection of ships that can be made to appear randomly throughout the galaxy. Fleets can also be made to appear by including them in dude resources.

LeadShipType ID of the fleet's flagship's ship class
EscortType (x4) IDs of the flagships escorts' ship classes. If you don't want to use four different escort types, you should still set the unused fields to a valid ship class ID. (you can set the min & max fields to 0 and just have the extra ships not appear)
Min (x4) The minimum number of each type of escort to put in the fleet.
Max (x4) The maximum number of each type of escort to put in the fleet.
Govt ID of the fleet's government, of -1 for none.
LinkSyst Which systems the fleet can be created in
    -1 Any system
    128-1127 ID of a specific system
    10000-10063 Any system belonging to this specific government
    15000-15063 Any system belonging to an ally of this govt
    20000-20063 Any system belonging to any but this govt
    25000-25063 Any system belonging to an enemy of this govt
MissionBit
    -1 Ignored
    0-511 The fleet will only appear when this mission bit is set
    1000-1511 The fleet will only appear when this mission bit is not set

Note: The MissionBit field is ignored when the fleet is pointed to by a dude resource.

Note: When setting up misn resources, you shouldn't make reference to a dude resource which contains pointers to fleets, as this will cause Override to behave strangely. Use only normal, single-ship dude resources in missions.