In order to fully exploit the design knowledge during the operation of mask manufacturing equipment, as well as to enable the efficient feedback of manufacturing information upstream into the design chain, close communication links between the data processing domain and the machine are necessary. With shrinking design rules and modeling technology required to drive simulations and corrections, the amount and variety of measurements, for example, is steadily growing. This requires a flexible and automated setup of parameters and location information and their communication with the machine. The paper will describe a programming interface based on the Tcl/Tk language that contains a set of frequently reoccurring functions for data extraction and search, site characterization, site filtering, and coordinate transfer.