btb:
> by chance, i happened to create a parameter which used a dash in the
> name, and was referencing it in another parameter, e.g.:
>
> foo-param = foo
> bar_param = ${foo-param}
>
> upon restart, postfix complained about this:
>
> postconf: warning: macro name syntax error: "foo-param"
> postconf: fatal: macro processing error
With $name and ${name, the name is limited to the character set
[a-zA-z0-9_]. Allowing other characters in those contexts names is
too problematic. It's not possible to rely on spaces to end the name.
Wietse