Not sure what they are referring to, but it may be that you can declare things as having one of several types (e.g. int|string|void) or even that something can be any type at all (i.e. turn off static type-checking for that thing)? I do not think the type-checker will ever randomly decide to just not check a type given that you have provided types for it to check, but it was a long time ago since I had to read or write any Pike code.