Declarative Requirement Statements

The Declarative Requirement Statement format is a direct assertion of one “...property that is essential for an IT system to perform its functions.” They are ‘declarative’ in that they do not imply any order or flow upon the information system. Such statements are usually part of a larger group or list of Requirement Statements, and can be documented at various levels --- from High-Level Requirements that are often documented first in a project, to detailed statements used as input to Design and as the source of Test Cases.

The common structure is: “…the System must .”

Variations on this structure include:

• Referring to the “Solution’ instead of ‘System’, as an information or other type of ‘System’ is not always what is needed to meet the Requirements of the business.
• Variations on the verb ‘must’, such as ‘shall’ or ‘will’; a ‘must’ statement is often interpreted as a mandatory requirement, while statements using other verbs mean the requirement is optional or ‘nice-to-have’. If multiple verbs are used in a set of Requirement Statements, the specific meaning of the use of each verb should be clearly defined.

Examples:

“The System will provide security that a Manager can only view salary data for their own reporting staff.”

“The System will calculate the monthly payment for a loan application, given the
• Interest Rate,
• the Amount Borrowed,
• and the Number of Payments & Payment Frequency”

Presenting large numbers of Requirement Statements can be a challenge, and grouping them by common attributes is one means of organizing the statements; one very common classification is the grouping of requirements as Functional or Non-Functional.

Requirement Statements can also be given a context by associating them with other documentation methods, such as Use Cases. This will be the topic of my next post.