Marcus Comstedt on LysKOM:
IIUC the target is supposed to be a MIME-type, which means that non-ASCII is simply not allowed. So you could check the min and max of the string to make sure it only contains ASCII and no control characters (such as NUL).
Huh. Didn't know that; the docs I was looking at didn't say, and the example I had used "STRING". But poking around on the internet shows some support for the "should be a MIME type" notion, and it answers my unspoken question "how in the world do you synchronize across applications", which doesn't affect my current project.
ChrisA