Here's an example:
private void btnUndo_Click(object sender, EventArgs e)
{
<<<<<<< .mine
=======
The third and fourth line are being added to other developers machines when they do an update with from my commit. I'm using SVN.
What is being added here?
You/Somebody had a conflict on the update/commit and you didn't resolve it before checking in.
The <<<<< and ===== is there to show you what part of the source code is conflicting, and you need to resolve those before you actually commit -- the commit may even have warned you about it, and you may have confirmed to SVN that it was resolved.
That's saying that there is a conflict in the file with that line, and that this is your local file that is in conflict. There is likely a "theirs" portion nearby (above maybe?) that represents the repository's code that doesn't agree with yours.
The other developer seems to be committing a file in conflict status.
svn commit doesn't allow you to commit conflicted file that are not resolved (you have to do an svn resolved first).
Perhaps a bigger question to ask is why/how he committed this file to the repository?
