The NILADIC statement has the form
and declares name (and name2, etc.) to be the name of a function with no arguments, and not to be taken for a variable where it occurs. Subroutines with no arguments do not need to be explicitly declared.
Note that this does not interfere with the use of that name with arguments as a function; it simply states that, if all arguments are omitted, the syntax FUN() is not necessary to avoid FUN, declared NILADIC, being mistaken for a variable.