Question: I have a tag with several changes on it whose base revision came from somewhere (branch? trunk? not sure.) I believe what happened was I checked out the trunk, made changes to it, then tagged from my working copy. I've tried to use the following command, but it doesn't say anything about the base. What I want to do is find the base and do a comparison between the tag and the base revision to see what changes were made between the base and tag.

```
svn log -v --stop-on-copy (url)

```

results in:

```
r3678 | my.name | 2010-12-23 14:44:40 -0800 (Thu, 23 Dec 2010) | 3 lines
Changed paths:
   A /tags/dir
   A /tags/dir/subdir
   A /tags/dir/subdir/subsubdir

My commit message.

```

Answer: 
You keep talking about the changes on the tag. However, tags should never1 be modified. Tags should be completely immutable1 and never modified by anyone1.

Anyway, if you looked at the tag's `svn log` message, you should be able to see the change there:

```
$ svn log -v --stop-on-copy (url)/tags/1.0

r3678 | my.name | 2010-12-23 14:44:40 -0800 (Thu, 23 Dec 2010) | 3 lines
Changed paths:
     A /tags/1.0 (from /trunk:2432)

My commit message.

```

And, if you aren't sure where you did this, you can simply do a `svn log` on the entire repository, and only look at the first few transactions since your change should be one of the first few changes.

---

1.In computers, *never* means sometimes in extreme circumstances. There will of course, come a time when you might have to modify a tag, but it should be very, very rare. For example, right after you just finished a tag, a developer comes and complains that they had to make one more change. Of course, you might simply be better off deleting the tag and recreating it.

I have a [pre-commit hook](http://dl.dropbox.com/u/433257/newest_svn_hooks.zip) that allows users to create a tag, but prevents users from modifying a tag once it has been created. You can configure it to allow only admins to modify tags just in case you actually have to do just that.
Figured it out. The container folder's log only shows the history for that folder. I had to drill down to the actual source folder and look at its history to see where things were coming from.

As it turned out, I copied from the trunk to my user directory, did a bit of development there, and tagged from the user directory.