RULE-UTILITY-FUNCTION BUSINESSCALENDAR ISBUSINESSTIME be of use?

Hi,

Initially i have a requirement to identify working hours using a business calendar and set a flag to Y for working days and N for non working days in an activity. I have done this as mentioned above.

now there is a new requirement where multiple oerators are there and they belong differnt time zones in US. I need to identify the working hours for the differnet timezones and need  to set the officehrsflag to "Yes" or "No" when an operator click on a button.

Please help me out how to identify the officehrs depends upon the operators time zones.

Thanks in advance.