[TRMW]
isometric=0
If isometric=1 is set in the DP4 configuration file then the terminal manager adjusts x_factor and y_factor so that a rectangle that has an equal width and depth in internal units appears as a square on screen.
It does this by increasing one or other of x_factor and y_factor as required. If x_factor is increased controls will appear slightly larger horizontally, if y_factor is increased they will be larger vertically. Font sizes are unchanged. The default for isometric (its value if it is missing from the DP4 configuration file), is 0, however it is set to 1 in the issued the DP4 configuration file. The value of isometric will only have an effect if your default font is NOT twice as high as it is wide. Note that the System font (at least on US Windows) IS isometric anyway. Setting isometric=1 when you use another font (such as MS Sans Serif) as the default font may change the size of maps on screen. Doing so will ensure the aspect ratio of printed maps is the same as displayed maps, though this will only be necessary if there is significant difference in how Windows realises the font when printing from on screen.
From 4.616 you can specify values for x_factor and y_factor in the DP4 configuration file. The only time you would be likely to need to do this is if you wanted to use a default font that was slightly smaller than your desired x_factor and y_factor. For example if you design an application to run full screen at 640*480 you can ensure it will also run full screen at 800*600 resolution, whether the user chooses "Large" or "Small" fonts by specifying x_factor=10,y_factor=20.
See Coordinate system for more information.