TM:- Tracing the test cases as per req.s & checking whether
all the test cases r passed r not

we use the tracibility matrix to cross check whether all 
the requirements are tested.
In this document we will listout, all requirements and map 
the test cases for each requirement. By using this, we can 
estimate how much functionality is tested(freezed).
Forward traceability is from requirements to design to code 
to testcases.
Backward traceability is on the reverse direction, that the 
end product has met the requirements or not.
Bidirectional Tracibility=forward tracibility + backward 
tracibility.