A system, method, and program enables a platform independent way for specifying a property, or function, of a program. Values of properties that are specific to a given operating system are treated as a variable in a program which enables it to run on multiple operating systems. This enables the program to be developed and run on different operating systems. The program reads in the properties and the values, or variables, from a script file into property objects. As such, variables that have meaning to a system can be put into the property object as the value for that property. To use the property by the program, the program sends a get call to the property object to get the value or to provide substitution of a platform specific value for the variable. Accessible to the program is a plurality of operating system specific code segments which define an actual value for the variable for the specific operating systems. Once the substitution is made, the program uses the actual substituted value for the process the program is carrying out. At the end of the program's process, the program saves the properties by parsing out the operating system specific value and inserting the variable back in. The program is then capable of being run on a different operating system. This provides a platform independent way for an install program to specify and use directories or other install properties; or for other programs to specify and use properties in general; i.e., by creating platform independent variables for properties.