> 1. can you explain how the sharing of subsystems work? Do subsystems share modules?
"System shares on subsystems" in the sense "Architecturally Divided to subsystems".
> 2. Two types of subsystems, modular and usual. Could usual be referred to as non-modular?
I think will beter "normal".
> 3. Regarding the number of subsystems. Is 9 the least amount for a base system and more can be added. This would mean that OpenSCADA could contain many more than 9.
If any user append self subsystem realisation into any module of the core subsystems then OpenSCADA will have more than 9.
> 4. The subsystem called "Special" is similar to the one listed in the module list. Could this be referred to as "Specialty"?
It can.
> 5. Transport protocol = Communications Protocol? (RS232, RS485, IP, DH485, etc ....) Given the answer to this how does that affect the list of modules because there are both communication protocols and transport protocols listed? 6. What is the difference between the two subsystems, transport protocols and transport?
Transport protocols is: ModBus, DCON, OPC_UA ... .
Transports is interfaces level: Ethernet sockets(TCP, UDP, Unix), Secure (SSL, TLS), Serial (RS232, RS485, GSM, Modem).
> 7. I would like to refer to "Archives" as "Histories", since this is a typical naming convention.
Yes it is, but in more other places already used "Archives".