Error messages are handled by the class tt(Err). This class defines the
content of various error messages, some of which are plain messages, and some
require a onfiguration line information (tt(LineInfo), cf. section
ref(TYPEDEFS)). The messages are selected using symbolic names defined in the
tt(enum Msg), nested under the class tt(Err). The following symbolic
names are defined:
    verbinsert(//msg ../../../err/err.h)

All members of tt(Err) are static. They are:
    itemization(
    itt(char const *src(ParamsSrc type))nl()
       returns the name of the parameter specification source tt(type)
        (cf. section ref(ENUMS));

    itt(std::ostream &msg(Msg err))nl()
       merely inserts the error message into the error stream, returning a
        reference to that stream;

    itt(std::ostream &msg(Msg err, LineInfo const &lineInfo))nl()
       inserts confguration source, line nr, and the error message into the
        error stream, ending in `tt(: )'. A reference to the stream is
        returned;

    itt(void specification(LineInfo const &line))nl()
       shorthand for using tt(msg(SPEC_ERROR, line)).

    itt(void multiplySpecified(LineInfoVect const &lines,
                                      std::string const &sectionList))nl()
       shorthand for using tt(MULTIPLY_SPECIFIED) in specification
        tt(sectionList), listing the info about the multiple specifications
        provided in tt(lines).
    )
