Which of the following defines a 'locked' expression?

A 'locked' expression is defined as one that cannot change. In the context of design software like NX, locking an expression ensures that its value remains constant throughout the design process. This can be helpful for maintaining specific relationships between components or parameters that are critical to the integrity of the design.

Locking an expression prevents accidental modifications, which can help protect key design intentions from being altered unintentionally. It essentially creates a safeguard so that users or the system cannot adjust that specific expression without first unlocking it.

The other options do not accurately reflect what constitutes a locked expression. For example, an expression that is permanently deleted would no longer exist and cannot be modified or locked. An expression that is only editable in the dialog doesn’t convey the idea of being locked, rather it highlights a limitation in how edits can be made. Finally, a temporary expression suggests that it exists only for a limited time and is subject to change, which is contrary to the meaning of a locked expression.