British Standard BS 6154 defines a standard syntactic metalanguage. This report first explains what a metalanguage is and why it is useful; the rest of the report is a guide and summary of the standard metalanguage. Many examples are taken from subjects outside computing, others come from Fortran or Pascal, two of the commonest programming languages. Important features of the standard metalanguage are that it can be typed easily and processed by computers. This report is based on an earlier one, NPL Report DNACS 47/81, now out of print.