Hi,
First of all, thank you Matthias for your thorough answer which I think illustrates the problem of merging message keys very convincingly. By the way, I hope no one feels offended. Please understand that after spending so much time (and nerves) on struggling with the various problems presented by split messages, we're keen to create some awareness among programmers and to help make translation easier and more efficient in the future.
In general, it's important to leave the messages whole as far as possible (even if it's several sentences that belong together).
Concerning the use/creation of common message keys (from whole messages), there's unfortunately no golden rule. The more standardized the message is, the more likely it works. That's the case with Add, Apply, Cancel, Continue, Delete, Discard, Edit, Finish, Go, Help, Log in, OK, Register, Reset, Save, Stop, Update or phrases like "This may take a while, please be patient." But it is not easy to decide without knowing the target language, and as we've seen, even Search and Approve are problematic. The same is true for Yes and No; when they occur together (as options), common keys are ok. In other cases, translations for No vary (in German Nein or Kein/Keine/Keiner) depending on the context. So if in doubt, please create extra keys, that's the safe way.
Anja
