By the way, I need help with how to type "the thin equal sign" (the green circle) in Mathcad 14.
Same way as the * and the +. If you create a math region and you type Ctrl-Shift-K (cursor gets red as in a text region) you can use literally any character in a variable name. Pressing Ctrl-Shift-K again brings you back to normal mode. That way you can use characters in variable names which normally would be taken as operators. The sam way you can also insert some spaces instead of using the underline character as you had done.
