How display mode description string that includes width, height, refresh rate and display index should look like?

W is width, H is height, f is refresh rate, D is display index

"WxH@fHz on D" or "WxH@fHz:D"

Or even make it more complex and instead of display index write its display name?

"WxH@fHz on HDMI" for example.

I kinda like the option with display name more.