Wanted to personnaly fix the format issue on this following page
http://en.wikipedia.org/w/index.php?title=List_of_device_bit_rates
the units 'Byte/s' are shown as '[[Byte/s'
They use {val|0000|u=foo}
I tested the template with know units 'm' and it worked but
unknow units like 'tmp' had the double bracket showing.
http://en.wikipedia.org/wiki/Template:Val
I don't know how to help more then reporting this.
Goodluck