The monadic operator null (⊙) is used to aid in resolving ambiguities with slash/slope as a function/operator.
That is, if the parser has trouble with a phrase using slash/slope where you mean that symbol to be a function, but the parser interprets it as an operator, or worse yet signals a SYNTAX ERROR, try using the Null operator.
For example, in L+//R the interpreter parses the lefthand slash as an operator whose derived function is +/. If you mean that symbol to be a function, use L+/⊙/R which forces the lefthand slash to be interpreted as a function. Alternatively, that line could be written as L+(//R).