Requirements for the software layer responsible for translating the Observing Block (OB) description into a set of executable sequencer commands and scripts have been defined. This layer is called the ``OB Compiler''. Compiler modules for the ALFOSC Imaging and Spectroscopy modes are the first to be developed and are expected to be ready for testing during the summer. The compiler module for FIES will be the next.
A interface that allows to control the execution of an OB in a verbose mode is being developed in parallel. This ``executer'' system will include a graphical interface that allows to execute as a whole, or in parts the resulting set of sequencer commands and scripts defined by the OB, with the option to stop or pause at intermediate steps, skip certain parts or abort execution at any time.