a method for the control of computer facilities , i . e ., functions , is disclosed . the method comprises the identification of a computer facility , such as printing , selected for manipulation of data . the method then identifies a source location of the data , for example by examining a uniform reference locator associated therewith , and then checking whether the source location of the data is valid for the performance of the selected facility . if the source location is not valid , the facility is not performed for the data and if the source location is valid , the facility is performed for the data .