Is "Good-Till-Cancel" order good for 90 calendar days or 90 working days?

Please tell me if Good Till Cancelled orders are good for 90 calendar days or 90 working days. Or, how are these 90 days counted.

This definition is vague,

Good ’til canceled (GTC) describes a type of order that an investor
may place to buy or sell a security that remains active until either
the order is filled or the investor cancels it. Brokerages will
typically limit the maximum time you can keep a GTC order open
(active) to 90 days.