A Maple Matrix is an rtable with subtype option Matrix.

The type(expr, Matrix) function returns true if expr is a Maple Matrix.

The type(expr, 'Matrix'(R)) function returns true if expr is a Maple Matrix with the shapes or options given in R (see Matrix for permissible shapes and options).

If R includes the name 'square', the Matrix dimensions are checked for equality.

Note:  It is essential to quote the word Matrix in this form of the calling sequence in order to avoid confusion with the Matrix(..) constructor function.