Firefox Bookmark Keywords

I had talked before about using Firefox's bookmark keywords, where you can type a (few) letter(s) into the address bar and it will go to that bookmark. This is even usable with arguments, so for example I can do:

gm Chicago IL

to get a Google Map of Chicago.

This usually works great, except when I want that page as it would be by default. Because Firefox uses '%s' to signify where the arguments would go, if I just type 'gm' and hit enter, Google Maps will instead look for a place called 's', which is usually in Mexico (strange).

The solution that I recently came up with was to put a space before the '%s'. It made sense when I came up with it, but now I can't vocalize why it would get rid of the %s if it is preceded by a space. But now, I can get to Google Maps proper with just 'gm'.