Not all requirements have equal significance in the architecture. Some play an important role in determining the architecture of the system, but others do not.

Deciding whether a specific requirement is architecturally significant is often a matter of judgment. Typically, these are requirements that are technically challenging, technically constraining, or central to the system's purpose.

These are good examples of Architecturally Significant Requirements:

• The system must record every modification to customer records for audit purposes.
• The system must respond within 5 seconds.
• The system must deploy on Microsoft Windows XP and Linux.
• The system must encrypt all network traffic.
• The ATM system must dispense cash on demand to validated account holders with sufficient cleared funds.