Currently the standard library includes one component in the simple_transmission_lines tool box.  A tool box is just a directory with the description of models in it.

Remember the arguments are case sensitive.

lossless_transmission_line

A lossless transmission line which is described by three arguments.

1. z0: the line impedance (in ohms)
   
2. theta: the electrical length (in degrees)
3. f0: the center frequency (in Hertz)