Note: This patch has been submited to drupal.org and is part of the module now.

If you need to add custom display modes in Measured Value Field this simple patch can accomplish this.

Open mvf.module and go to

function mvf_widget_settings($op, $widget)

Change

$options_single = mvf_get_display_modes_single();
$options_range = mvf_get_display_modes_range();

to

$options_single = module_invoke_all('get_display_modes_single');
$options_range = module_invoke_all('get_display_modes_range');

Now you can create functions in your modules that can imlepent new display modes

function mymodule_get_display_modes_single() {
  return array(
      'f|s' => t('"From" value + Symbol'),
  );
}
function mymodule_get_display_modes_range() {
  return array(
      't|s|-|f|s' => t('"To" value + Symbol + Space + Hyphen + Space + "From" value + Symbol'),
  );
}

This example swaps From and To values and adds symbol to both numbers