The validation of a system is done following a bottom-up approach. First each card of the sub-system is tested out. These cards are then assembled to make a sub-rack (also called a 'bin').Once the required number and type of sub-rack are tested, they are assembled in racks. These racks are then interconnected together to form the complete system. At each stage of the assembly, certain tests are performed to ensure functional integrity and stability of the system.
These tests are classified, as outlined above, into there groups, viz:
1.Card level test
2.Sub-rack level test
3.System level test