Case Analysis and Mode Analysis

A chip design usually has different operating modes, such as normal operating or "mission" mode, test mode, scan mode, reset mode, and so on.
Typically , you analyze the timing for each mode seperately.

To place the design into a specific operating mode, you can use a technique called case analysis. You apply a constant value or a specific transition to an input port with the set_case_analysis command.

For example,
If the test mode is activately by an active_low input pin, you can set that input to 0 for analysis in test mode, or set it to 1 for analysis in mission mode.
If there is an active-low reset input, you can analyze the circuit timing for a reset operation by applying a high-to-low transition on the reset pin.