COMMAND_NAME is a column in the User Calc function IMUC. The tab in IMUC for COMMANDS shows a table with the first column listing a 'Command Type' followed by a 'Command' and then the 'Command Name' followed by a 'Description'.
Example:
Command Type
Calculation XPPT Exit the Pay Point Set UC in progress to immediately proceed to 99999
In this example 'Exit the Pay Point Set' is the Command Type.