My apologises in doing a bit a research I realise it is a micro USB B port and not a mini USB port as I stated above. I am always getting them mixed up.
Ch23 I think that using 9mm is too large, this page
http://www.symmetron.ru/suppliers/hi.../hirose_ZX.pdf indicates that the port is 7.5mm, with a bit extra for the plastic hole I think that 8mm is probably a better estimate for the real size of a micro USB B port.