This is a method to let you reset cameras in Gmax with a right-click on the viewport as in 3ds Max. This is useful when after previewing different views with BAT scripts you are left with an ortho view locked in where perspective used to be, or you accidentally shift one of the top/left/side views into perspective and want it back.
In Gmax, go to Customize menu > Customize User Interface > Quads tab, then drag from the left side list under "All Commands" over to the right side list, under "TRANSFORM" here.
Here, the following items have been added to the top of the "TRANSFORM" section of the menu: Perspective User View, Left View, Top View, Front View, Separator.
As a final step to make these changes "stick" between program launches, click Advanced Options under the right side list and click the Save as Startup button, accepting the "are you sure" dialog.
Now you can right click in the "Camera Z5" viewport and select the Perspective view to get back to work quickly, after previewing different angles of your model.
Other uses for this general method
Add commonly used actions like "Boolean" and "Convert to Editable Mesh" to the right click menu, to eliminate repetitive actions.