In addition to the options risks described earlier in this Chapter, the Central Bank is conscious of the other risks also associated with options, e.g. rho or interest rate risk (the rate of change of the value of the option with respect to the interest rate) and theta (the rate of change of the value of the option with respect to time). While not proposing a measurement system for those risks at present, the Central Bank expects banks undertaking significant options business, at the very least, to monitor such risks closely. Additionally, banks will be permitted to incorporate rho into their capital calculations for interest rate risk, if they wish to do so.