obligatory
arrangement
bare necessities
basic training
boundary condition
briefing
call for
called for
catch
clause
clearing the decks
condition
demand
demand for
demanded
desideration
desideratum
donnee
equipment
escalator clause
escape clause
escape hatch
essential
essentials
familiarization
fine print
fixing
foundation
given
grounds
groundwork
imperative
indicated
indispensable
irreducible
irreductible
irreplaceable
joker
kicker
limiting condition
makeready
making ready
manufacture
mobilization
must
must item
necessaries
necessary
necessities
necessitous
corequisite
determinant
healthiness
precondition
qualification
requisite