F	dynamic force
dF	dynamic force increment
s	disk deflection
ds	load deflection increments
LO	number of wraps
M	foil mass
O	single wrap
VAL	value of used stretch film
EI(M)	magnitude of the force F exerted by the stretch film relative to the mass of film used (M), i.e., F/M
EI(O)	magnitude of the force F exerted by the stretch film resulting from wrapping the load with one layer (L) of film, i.e., F/L
EI(VAL)	magnitude of the force F exerted by the stretch film resulting from using film of a specific value or grade (VAL), i.e., F/VAL