While additive manufacturing objects are described by the STL and AMF standards, the protocol controlling the fabricator is typically machine-specific. In this paper, we explore a system architecture that converts geometric data into control processes for equipment. We propose a new Extensible Digital Fabrication Language (XDFL) and an interpreted ToolScript language that describes how a geometry is translated into machine commands. An initial implementation of this system architecture was created and deployed as part of the Fab@Home project. The introduction of a standard process control language will decouple process planning from the equipment manufacturer, thereby catalyzing the introduction of new equipment and development of better process planners.