Why does webTOD require me to enable 'pop-ups' for it to operate properly?

webTOD uses Javascript, a browser-based scripting language, to perform various data validation checks on the information you enter into the webTOD calculator before sending the information to our webTOD server. When you click on the 'Calculate Deductions' button, instead of sending the data directly to the webTOD server through an html form POST, the webTOD calculator uses a Javascript program to ensure that there are no problems with the data you entered. If the information you entered passes these validation checks, the Javascript program will send the data to the webTOD server and open a new browser window for the server to display the calculation results in. The use of Javascript data validation on the 'client-side' (browser) reduces the processing load on the webTOD server and also reduces the amount of network traffic between the browser and the server, allowing the webTOD server to perform more efficiently (and do more calculations for everybody!).