Wrong: The requirements are implemented
incorrectly in the application.
Missing: When requirement given by the
customer and application is unable to
meet those application.
•Extra: A requirement incorporated into
the product that was not given by the
end customer. This is always a variance from
the specification but may be an attribute
desired by the user of the product. 

Tbere are different defect categories:
Wrong: When a requirement is implemented incorrectly
Missing: It is a variance from the specification,
an indication that a specification was not
implemented or a requirement of the customer is not met
Extra: A requirement incorporated into the
product that was not given by the end customer.
It is considered as a defect because it is
a variance from the existing requirements

slate