When an external program reports a problem with a traffic control element, it can include an identifier, which is then translated to the source code location by tcc.
For this purpose, tcc reads standard error of the external
program, and tries to translate all strings of the form
[<type@identifier>], where verb is
one of the element type names described in section 5.3.1,
and the identifier is the corresponding element identifier described
in that same section.