Hi,

How can I compare my original skyrim with mod files to see what has been changed?

And to have a clean mod!
If I have misplaced some objects, how can I fix this? So that the * marker is gone?

thanks for help

There are several ways to do that. There are some 3rd party tools that are now very close to becoming available. My understanding is that TESVSnip is being updated to be "safer" to use. TESVEdit is in closed beta. TESVGecko is in open beta and you can find it here: http://www.darkcreations.org/forums/files/file/388-tesvgecko/ While Gecko is still beta and no where near finished, it if functional enough to show you what is edited by your mod and let you remove anything you want. They have not completed the decode so you will need to use it in conjuction with the CK to see what you are removing.

And then there is always the Details window in the CK itself for someone who is not interested in using outside tools. That is a somewhat complex process and I wrote a description of it a while back on another topic here. I will copy that into the next post for you to see.

Note the FormIDs (a disposable screenshot works well) of the stuff you want to remove, then File > Data > Details for your plugin and hit the Delete key on each errant form after sorting the shown list by FormID. After saving, the "Ignored" forms will be purged from the plugin rendering it 'clean'. When TES5Edit is out, it'll be a lot simpler/faster to perform such an operation.

First and formost. ALWAYS back up your plugin file before you edit it. Even if you do nothing wrong, there is some pretty high risk that the CK will still botch it up and corrupt your file. Sometimes it is recoverable and sometimes it is not. If you are deleting navmesh records (never delete the NAVI) then your chances of having problems go up dramatically in my experience. You can do it, but it might take a few tries. That is above the level of this discussion but I added a little about it in the tips. If you need to delete NAVM records, best of luck, you're going to need it.

So lets give it a try.

• Choose your plugin in the Data window, make it your active file and open it. It may already be your active file, but there cannot be any changes to save when you start this. So if it is active, hit save before you open the Data window.
  
• If your unwanted edits are in a cell - locate that cell in Cell View so you can see the edited objects and their Form IDs. If they are just object edits with no cell, find them in the Objects window so you can see their Form IDs. You need to know their form ids and you find them in the cell window or objects window depending on what they are. The edited objects will have a * by their Editor ID.
  
• Open the Data window and click details with your plugin selected.
  
• When it asks if you want to use an empty list to save memory, say no.
  
• Next it asks if you want to use form strings, say no.
  
• When File Details opens up, drag the sides out so you can the columns.
  
• The most important column, Form ID, is collapsed just to the left of the Offset column. For our purposes, the other columns are pretty meaningless, but they had to make it as inconvenient as possible.
  
• Sort the list by Form ID and find the Form IDs with the edits you want to ignore and select them in the File Details window. You can select multiples by holding down CTRL.
  
• With the Form IDs selected, hit the Delete key and say yes to the warning dialogue that pops up.
  
• When you are done, click on Close at the bottom of the File Details window.
  
• Select OK in the Data window and let your plugin load again. Your edit should be gone, but save the file again at that point.

Tips:

• Don't try to do too much at one time. The CK crashes during this process ALOT - OFTEN - MOST OF THE TIME! Usually at the reload step at the very end. If you just spent 30 minutes locating and ignoring your dirty edits all over Skyrim, you will have wasted your time. Do a few at a time, no more than one cell so you know where you were.
  
• If you want to delete actual Cell edits, make sure you ignore all of the edits in the Cell first, save and reload the plugin and then ignore the Cell.
  
• Test often and carefully. Clean a cell or a few edits and test the mod. Sometimes everything went just right, but your mod will crash Skyrim or crash the CK so you can't even get back in to try to fix it. Like above, if you just cleaned a bunch of stuff, you will have no idea where you went wrong, and you will have nothing to show for your time.
  
• Just because the CK or the game crashed the first time you loaded your newly cleaned mod, doesn't mean it is hopelessly lost. Try again, an again and again. I have had some that took a dozen loads in the CK before it had completely repaired all of the damage done from navmesh edits. Navmesh edits always seem to botch things up but it appears that it takes multiple loads in the CK to get everything updated - maybe it is repairing the NAVI. I don't know, but it usually works. Sometimes, when you load it back into the CK, it gives you multiple errors about missing stuff. When that happens, kiss it goodbye and go look for your backup.

What things are safe to delete when working on your mod and what things aren't? What about changing names?

I haven't had any problems changing names. The CK seems to track name references pretty well.

If you mean ignoring edits in the Detail View, I would have to say the only references I have had troubles from deleting have been navmesh. Doing that can cause the CK to crash when you try to reenter the affected cell. If you are persistent, that may correct itself after several attempts to enter the cell. The CK seems to have the ability to heal some problems on its own.

If you are talking about deleting directly from the cell, never delete vanilla objects and deleting vanilla navmesh islands, so that you delete the entire record will cause some odd recurring error to pop up every time you load the cell in the CK.

Many thanks for the detailed explanations.