Testable Requirements can also be used to measure the thoroughness of test cases as illustrated in Figure 5.  

High Level
Requirement (HLR)
Testable
Requirements
Number
Tested
Percentage
Covered
Business
  Accounting
942
222
24%
  Administration
120
24
20%
  Audit and Control
225
98
44%
  Editing Functions
526
89
17%
  Update Functions
450
54
12%
  Maintenance
789
234
30%
  Conversion
2,500
1,200
48%
  Security
569
0
0%
  Reporting
3,590
2,400
67%
  Subtotal
9,711
4,321
44%
Technical
  Communication
1,500
17
15%
  Interface 1
225
180
80%
  Interface 2
369
200
54%
  Subtotal
2094
397
19%
Total
11,805
4718
40%
Coverage Status
Figure 5

In this example, the first column lists the high level requirements.  The second column lists the number of testable requirements associated with the corresponding high level requirement.  The third column lists the number of testable requirements that are validated by test cases.  The fourth column lists the percentage of testable requirements that are "covered" by test cases.  This measure of requirements coverage is a very powerful measure and gives important insight into the adequacy of the testing.