[OT] IPTC-Tags: Difference between "Caption" and "Subject"

[Peter2]

Independent from XnView I try to understand the definitions of some IPTC-tags, and with my limited knowledge of English the tags "Caption" and "Subject" seem to be nearly the same thing ...

What is the difference?

I have to describe scanned "wiring schemes" (wiring diagram), where I have
- a "main title": "Rockefeller Centre, New York"
- 1-or two subtitle: "Scheme high-voltage supply, 2 level, room 999"

Which tags would you use for the both types of information?

Regards

Peter

[xnview]

you have that

[Peter2]

I started here - and I'm insecure what to select ..
http://www.exiv2.org/iptc.html

Peter

[marsh]

Perhaps this very similar reference is also useful:
http://www.controlledvocabulary.com/ima ... #IPTCchart

[Peter2]

Thanks marsh

one hint more, but I'm afraid that the "Philosopher's Stone" is not find yet ...

Peter