I used to have difficulties with this, but if you apply the system metaphor those problems become less of a problem. In your example, you're dealing with a fil

I used to have difficulties with this, but if you apply the system metaphor those problems become less of a problem. In your example, you're dealing with a file system, so the file is the entity and everything else is just a property of that. With regards to source and destination, I find that people tend to struggle with this, so instead I tend to think about the entity in question (in this case a file) and the target entity (eg a remote file system). You don't need to add more words to make it obvious. Just be concise.