Hi,
You can open files for either reading and writing via ftp (but not both simultaneously).
This is what the php manual says.
The a+ option opens the file for both reading and writing. That doesn't work.
I'm not shure if you can open a file in append mode at all. I don't think so. But the modes "w" and "r" should work.
If "a" doesn't work you could open the file in "r" mode and write it to a file on your server. Then modify the file and put it back to the remote server with "w" mode.
Greetings,
Thomas