I finally found the table of Mach parameters again. It is in Mach3Mill_1.84.pdf section 10.
It lists numbers starting with 5161 = G28 home X and continues to 5326 = Work offset 6 C and then states
"And so on every 20 values until" and then the chart continues with 10281 = Work offset 254 X until 10306 = Work offset 255 C.
Then the page ends with
"A Mach3 machining system maintains an array of 10,320 numerical parameters. Many of
them have specific uses. The parameter which are associated with fixtures are persistent
over time. Other parameters will be undefined when Mach3 is loaded. The parameters are
preserved when the interpreter is reset. The parameters with meanings defined by Mach3
are given in figure 10.1"
Does the last line mean that I am free to use any parameter NOT listed in figure 10.1?