The part of capital issued only at the time of liquidation of the company is

Reserved capital is set aside and only called for payment if the company is winding up. It’s kept in reserve for emergency liquidation situations, not for normal operations.

Called-up capital is requested during normal operations. Issued capital is the total offered to public. Paid-up capital is what shareholders have actually paid. None of these are specifically for liquidation only.

Think of it as emergency capital, reserved for the worst-case scenario of company closure.