MXBLOCK mat mat1 mat2 mat3….
Outputs a “stacked” matrix mat.ufm, built from the input matrices mat1.ufm, mat2.ufm, etc. etc. in order. The explicit list of input matrices may contain up to 8 inputs (and clearly must have at least two in order to make sense).
N.B. The matrices are stacked “horizontally” in blocks, as appropriate for time periods; cf MXSTACK.