Ansys APDL : use of the MVERT_6P function

I am decrypting an old ansys apdl code. This code uses the MVERT_6P function like this: MVERT_6P,A1,A2,A3,A4,A5,A6,'MR0_R1',PAS. I can't find any information about this function in the Ansys help.
A1,2,3,4,5,6 correspond to 3D coordinate points.
PAS=1
This matrix, MR0_R1, is the transition matrix from R0 to R1.
My question is : How is precisely this matrix constructed via the function MVERT_6P ? Thank you.

I think this function builds a matrix named MR0_R1 with the following information:
A1,2,3,4,5,6 correspond to 3D coordinate points.
PAS=1

MVERT_6P seems to be an APDL macro written by someone at your organization. And not an Ansys Inc APDL command or macro. You can check

install directory\ANSYS Inc\version number\ansys\apdl\

(or similar for Linux) for mvert_6p.mac. It is possible to have a macro library; see the APDL command /psearch in the Mechanical APDL help command guide. If you start Mechanical APDL in interactive mode then issue /psearch,list there may be a path listed that would be to a macro library. Or possibly the value of the environment variable ANSYS_MACROLIB which is an another way of specifying a macro library location. Good luck.