I think , don't know, the .1 is an indicator of an improvement like diesel engine oils going from CC to now CJ-4 but backward compatible in equipment that used the older oils. I've been out of it too long to 'know'.
If you really want to know then get the mfgr. name and tel number and call them. Most good oil co. have people who are willing to help, at least in my experience.
Also a lot of good hydraulic shops may know.