DisponiBox® or AvailaBox™ is the component of the AvailaBility Information Système: AvailaBIS™. Others components of the AvailaBIS™ are :
- AvailaBase™ - Availability Bases
- Availability
Supervision Centres (ASC)
DisponiBox® uses the availability indicator, noted Dg for the global value. Dg is defined as follows:
Dg= -
log Kg [HeB]
Dg = 1 HeB for Kg = 0,9998
where HeB is the unit of availability.
This formula uses the value Kg , the availability factor, known in the field of analysis of reliability, deified as follows:

MTBF - average time between two failures and MTTR - mean time to repair, 0 < Kg <1.
Values MTBF and MTTR are provided by the manufacturers and their networks of service.
The unit suggested, named `HeB' honors works of Dr. Henryk Baczko, especially the index and the unit of availability suggested in his thesis in 1975