The present invention discloses a method and system for specifying and executing computing tasks in a preboot execution environment in general, and, in particular, a method and system for generalized imaging utilizing a language agent and encapsulated object oriented polyphase preboot execution and specification language. The target customization is advantageously accomplished by encapsulating target dependent parameters in specification files. The target specific parameters are resolved at appropriate execution time when the parameter information becomes available. Such approach simplifies specification of complex tasks to a merely few lines of code. The approach of the present invention nevertheless affords reliable, robust, and accurate performance, because the pertinent parametric information are resolved only when they can be accurately ascertained. Furthermore, the specification encapsulations are themselves a part of the image set, providing self-describing images with self-contained imaging methods. The result is a robust, reliable, flexible, and simple method and system for centralized maintenance and management of client devices in a networked enterprise computing environment with a lower total cost of ownership than existing products.