<p>I'm using caml query to select all documents which were modified or added by user. Query runs recursively on all subsites of specified site collection.</p>

<p>Now problem is I can't get rid of folders which are also part of result set. For now I'm filtering them from result datatable. But I'm wondering: Is it possible to filter out folders from result set just by using caml?</p>

So, i figured it out :)
You can use FieldRef='ContentType' in your caml query and specify typr of content type which you want to select or exclude from select.
So in my case I've added this condition to my caml expression:
```
<Neq><FieldRef Name='ContentType' /><Value Type='Text'>Folder</Value></Neq>
```
NOTE:
There are problems in multi language setup. Name of content type can be different, so it is good to get names of content types from resources
UPDATE:
It looks like I was too quick in my assumptions. I need to filter out all contett types based on folder content type, because in our projects such content types are used :(
I was not able to create workable query in caml, so I added view field element to my query which selects ContentTypeId of list item and I filter-out rows which are based on folder content type.
Code to do this is trivial, but it bothers me that such simple task cannot be done by pure caml.