Depends on use cases we write test cases

We have tracebility matrix 

by referring thet we will decide whether we will decide we 
cover all the functionalities or not?

Test Cases are written the requirements given by the Cust 
and realted to use of software(to some extent).Test Cases 
should or say Must cover all the things given by the Client.

Test Cases Contains:
Sl no 
Desc
Input
Expected Result
Actual Result
Status
Comments

RTM or Req'ment Tracemabilty Matrix sees whether all TC's 
are covered.

Test case is prepared based on the BRS, SRS UCD documents. 
There are two types of techniques are used 
1. BVA
2. EP.
By LOOKING AT the traceability matrix we can check all the 
test cases are covered.
By looking at the traceability matrix we can check all the 
test cases are written as per srs brs documents

u can write test cases in qc, or in excel etc. test cases 
are written by requirement study and from the prepared use 
cases. 
--------------
items in test cases(depends from org to org)
id, name, author, date,etc
description of the test
precondition
data
post condition
expected result
actual result
---------
we can develop a traceiblity matrix to determine the 
coverage. it is difficult to cover all the functionalities 
but the major should be covered. this requires an efficient 
team.