Lines with the following form are the basis of Middle code:

[ @out @in ] (T1, T2, ...  Tn)

Options start with an @ symbol. @out and @in are used to control the output. If you specify neither, both input and output code will be created. Specify just @in or just @out to tailor the output from the C++ Middleware Writer (CMW). After any options, a list of C++ types is enclosed in a set of parentheses. One or more of these lines are wrapped by a name and a closing brace -- } -- like this:

local_messages_front
  @out (marshalling_integer, const char*, int64_t)

  @in (bool)
  @in (std::string)
}

Based on that input, the CMW creates a local_messages_front namespace in a file called zz.local_messages_front.hh.

To comment out some Middle code, use // as usual. ~