In the first two calling sequences, the type command checks if expr is a valid nonempty Maple list or set. It returns true if expr is a list or set containing at least one element and false otherwise.

See the list and set help pages for a description of the list and set datatypes.

In the third and fourth calling sequences, where K is a specified type name, the type command checks whether expr is a nonempty list or set whose entries are of type K.  That is, type(expr, nonemptylist(K)) returns true if type(expr, nonemptylist) is true and type(x, K) is true for each entry x of expr. Sets are checked in a similar manner.

See the type help page for a description of valid types in Maple.