Per Mx manual, 6th edition:
Table 4.1 - matrix types and their free elements
Table 4.3 - Examples of use of the Matrices command to specify the dimensions of different matrix types
Table 4.5 - matrix functions
Some of table 4.5 has been implemented, but not all. What is really needed is the text descriptions of all the matrix operators and functions, so that we have online & pdf documentation of what the matrix operators and functions actually do.