NUMBER

NUMBER UNIT[new number-id]
NUMBER FACTION[new number-id]
NUMBER SHIP[new number-id]
NUMBER BUILDING[new number-id]

This allows you to assign a new number to a unit, a ship, a building or even your own faction.
If the number is already occupied, the number will not change.

Units, ships, buildings and factions can be given numbers in the usual range (up to four digits 0-9, a-z).
Leading zeros are not allowed. Without specifying a number, a random number is chosen.