Currently four instrumented widgets are included in the Eco Lab distribution. The first time these widgets are called, they instantiate themselves in a separate window. This follows the philosophy that initialisation should be a transparent operation. A number of these widgets depend on the BLT toolkit, so it is wise to include BLT at the compilation stage. Each widget is independent, and so multiple instruments can be operating at the same time.

Each such widget creates a new namespace x, the name of which is either supplied by the user, or generated from the arguments. Also created is a window heirarchy starting with .x. The widget command returns the namespace name which can be captured for future reference.

One of the uses of this namespace is to call the widget specific print command, which dumps a postscript representation of the widget to a named file. For example, a plot window start with plot nsp ... can be printed to “” using