tt(IFEQUAL) expects four argument lists. It tests whether its first argument
is equal to its second argument. If so, the third argument is evaluated,
else, the fourth argument is evaluated. All four argument lists must be
present, though all can be empty.

    The first two arguments of tt(IFEQUAL) should be integral numeric
arguments. In order to determine whether the first two arguments are equal,
their values are determined:
    itemization(
    it() If the argument starts with an integral numerical value, that value
is the value of the argument.
    it() If the argument is the name of a counter, the counter's value is the
value of the argument
    it() If the values of the first two arguments van be determined
accordingly, their equality determines whether the true list (when the values
are equal) or the false list (when the values are unequal) will be evaluated.
    it() Otherwise, tt(IFEQUAL) evaluates the false list.
    )

    Example:
        verb(
    IFEQUAL(0)()(\ 
        0 and an empty string are equal
    )(\ 
        0 and an empty string are not equal
    )
        )
    Please note the preferred layout: The first argument immediately follows
the function name, then the second argument (the em(true list)) is indented,
as is the em(false list). The layout closely follows the preferred layout of
tt(if-else) statements of many programming languages. 
