In the domain of Supervisory Control and Data Acquisition (SCADA), signi?cant challenges reside in the variety of proprietary interfaces and protocols which accompany the components and devices provided by different manufacturers. The Facility Control Markup Language (FCML) is designed to provide standardized and uniform access to different devices which usually only adhere to proprietary interfaces and protocols. As an application of the Extensible Markup Language (XML), FCML is designed as an open and extensible standard which can easily be adapted and extended to include requirements of future applications and devices. The subjacent vision includes the conjecture that web-based SCADA systems are very promising for a wide range of SCADA applications, for reasons of modularity and ease of deployment.