I'm not sure that there's a particular format for *.bin except that the data is in binary format. Numeric data has been converted to a machine readable format. This allows a faster loading of numeric data, etc. I often save record structures in binary form for speed of loading. There is no conversion of ASCII information to the data the programs use.
As cipher17 noted, use a hex editor. There are some excellent 'free' ones out there...
Many hex editors have two windows... one that shows the ASCII character and the other holding the hexidecimal value. Look to see if there is a pattern in the ASCII window; this may yield the length of whatever 'records' they have used. It really helps if you have one of the records converted to numeric value. It's a matter of looking at the hex value for the numeric value. You may also require determining if numeric variables are single or double or something else...
Start with the easy ones first and then fill in the blanks... good luck... I recently unravelled some climatic data, having the Fortran source for the 'encoding'... it was not pretty; it looks like the original record had been added to by various programmers over the years... but, by adding to the original source... after several iterations, it was really strange.
