for example - take this raw file (.PEF from Pentax *istDL) - http://www.box.net/shared/mp64f1s6e1 (~10mb)
aperture = F22 and exposure bias = -1 (PhotoMe report these correctly)
however if we will be using <F-Number> and <Exposure Bias> tags in XnView we will see "-3.6" instead of "22" and "-30198989/33554432" instead of anything more user friendly like "-1"
screenshot :
