Emu provides a set of extensions to the core Tcl language consisting of commands for creating and manipulating the central Emu data-structures. These structures, or objects, correspond to: database templates, hierarchies and sampled speech data. Most of the Emu commands are implemented as sub-commands of one of these objects. The most important of these is the database template since the Emu core library uses this to define the structure of the database and the options that are legal for creating and manipulating hierarchies.