Statements can be numbered and given a reference key so that
they can be referenced in a LATEX document using a \ref{} command
(see section 4.2 of [3]).
This is done as follows:
\STMTNUM{<space>}{<key>}
The argument <space> is the amount of space to be left between
the text and the statement number. This is a length that is specified by the
user, and generally will require some experimentation in order for it to look nice.
The argument <key> is the reference key
used in the LaTeX \ref{} command to refer to the given
statement.
The default numbering for statements is arabic. However, it can be changed
by a suitable \renewcommand{}.
An example is provided in the next section.