When I want to create an omod of my downloaded EE (enhanced economy) I get this warning:

Warning - this folder contains esp files in sub directories.
It is possible that this mod has been packed in a non standard way, or that it contains multiple versions.
You may have to attach a script to this omod to tell obmm what to do with any optional esps.
If you do not know how to script, copy the mod to a new folder and set id up as you'd like, and then use "add folder".
Do you wish to continue?

What does that mean?

Don't worry about it, it's standard with most complex mods.
You may notice that it recommends attaching a script to the omod - It already has one, so it's all good.

Ok, thanks. Can I make an omod for almost all mods or do they need the omod conversion data folder inside for it to work?

No you can not, as you mentioned a mod indeed needs omod conversion data in order to be used as a omod.

Hmm, but I just created Midas Magic as omod, this is no good then?

If there was omod conversion data then you are ok, otherwise i guess it will not work?

There ain't none...I'll check later if it works or not.

Actually, you can. Even mods packaged for BAIN can be manually converted to OMODs so long as you are familiar with the proper file structures of each along with what the end result needs to look like. There are, of course, exceptions but they are rare.

I myself am now converted to BAIN, but my first play-through was exclusively OMODs plus a few manual installs from before I got the hang of things.

-Decrepit-

Alright, thanks. I thought so...

Seems that one is never to old to learn.

You're right, especially when it comes to Oblivion and modding

Also, simple mods can easily be converted to omods without conversion data. When I say "simple" I mean mods that only have a plugin and either a bsa or meshes and textures folders. OBMM is set up to recognize certain structures, so you can create an omod by simply adding the archive. If you see a mod with a whole bunch of directories with numbers in front, like 00 Core Files, 01... then that mod has been packaged as a BAIN and will need omod conversion data (to tell OBMM what to do with all those directories) or you will need to repackage it yourself. Have a look at http://www.tesivpositive.animolious.com/ for more info on this.