There appears to be some confusion on these terms relative inter-company compatibility.   Maybe a layman's view will clear things up a little bit:

• CAN -- This is a communications protocol, something like Ethernet.   Many companies are using CAN systems to send digital messages between components.  However, having a CAN backbone in a system does not imply ANY compatibility with hardware from other vendors.   It may being used as a proprietary communications framework.
• ISO -- Clearly, ISO is a standards organization that covers a gazillion different standards.   Saying that something is ISO compliant, technically, does not mean anything.  However, I think most of the use of the term ISO that you see on this forum is really implying something more than ISO.  It is actually implying ISO 11783.
• ISO 11783 -- this is the ISO document that specifies how CAN is used for inter machine communication in agriculture.  There is J1939 as a North American standard that is very similar, but developed for truck and construction???, and there was a german standard that was very similar.  For agriculture, ISO 11783 was developed to merge these two similar approaches into a single standard.

As Torn as indicated several times, the 11783 spec covers lots of different things.   The acceptable connectors, the electrical specification, the message format, the message content (this is the difference between 11783 and just CAN), and the functionality of various system components: virtual terminals, task controllers, equipment control units, bridges, desktop interfaces, and data dictionaries, for example.

Within ISO 11783, there are "levels" of compliance.   The spec is incredibly complicated and powerful.  If it were required to implement it all at once, there would be little chance of adoption.  So while the spec for a specific area might document 10 different capabilities, a "level 3" compliance might define compatibility with the fist 4 capabilities.

When you here that being CAN based has no significance for inter-company compatibility... I would have to agree.  When you here that "ISO" compatible machines may still not work together... then you might have to do more digging.   If a machine required a level 4 virtual terminal interface, and a tractor only has a level 3 interface, then some features might not be available.   And, as Torn points out... there is a big difference between a virtual terminal and a task controller.  So things like the GS3 being ISO compliant means that you can plug in compliant devices from other vendors for monitoring and manual control.   But it does not necessarily imply that you can do variable rate controll or data logging, as these are part of the task controller... not part of the virtual terminal.

One of the most interesting things that I found last spring was that people were running White planters as implements with the GS2 operating in virtual terminal mode.   And the GS2 task controller was logging compliant data from the white planters, but was actually logging the data into the proprietary GS2 format, rather than the ISO compliant desktop data exchange format (part 10 or 11 of the spec... I forget which).  

So, Ron... you are right.  During this transition period we are going through... you do indeed have to do some homework to know what "ISO Compliant" really means for your situation.   But, in general, it appears that the hardware from one company that can operate as a virtual terminal with a recent level of compliance, and be used as the interface and manual control console for a rapidly increasing range of equipment control units (ECUs).   From where I sit, the momemtum for this has rapidly increased.  

For those of you much more versed in this technology than am I... is an auto-swath unit a task controller?  Or is it an ECU?   What about a guidance capability?