OSI falls under GOSIP - which was government (or at least DoD?) mandated attempt at OSI stack. DECnet Phase V is also OSI based, but yes, DECnet Phase IV might

OSI falls under GOSIP - which was government (or at least DoD?) mandated attempt at OSI stack. DECnet Phase V is also OSI based, but yes, DECnet Phase IV might have windows options, so could XNS. Windows could also easily adapt to new physical layers. Windows networking stack was easily extensible, something that to this day Berkeley-derived ones have issues with (Sockets, being "temporary hack", lacked features to handle multi-stack well). A non-trivial reason I heard for popularity of Solaris in certain telcos was that it offered XTI interface, meaning much easier access to ISO/OSI related protocols present in many areas of telco gear.