Apple Macintosh System 7.5 - Manual (Page 29)

Application programs and System 7.5
Most currently shipping versions of application programs are compatible with
System 7.5.
Upgrades are available through dealers for earlier versions of most programs.
Order these early in your planning process, so you can have the compatible
versions at hand when users upgrade.
Network compatibility
When upgrading system software on networked computers, you need to
consider three aspects of your AppleTalk network:
m AppleTalk software and driver versions
m internet routers (if you have multiple, interconnected networks)
m network services, such as file servers and mail software
AppleTalk Phase 2 software and network drivers
AppleTalk Phase 2 is an extension of the original AppleTalk network
protocols that supports larger internets with many more devices per network
and allows more efficient routing and zone management.
The AppleTalk software installed with System 7.5 is intended for use on
AppleTalk Phase 2 networks. Apple recommends upgrading all AppleTalk
networks to Phase 2, which has been the AppleTalk standard since 1989.
26 Chapter 3