OpenOffice uses a file format called the OpenDocument Format (ODF). These files have various extensions, such as .odt for Writer and .ods for Calc. PowerGREP comes preconfigured to handle all the extensions with the file mask *.od[bcfgimpst]. This format is officially documented, and even standardized. Still, it is incredibly complex, simply because OpenOffice offers a tremendous amount of features.
ODF files are technically ZIP archives that contain a bunch of XML files along with support files such as images. While PowerGREP treats ZIP archives as compressed folders, transparently zipping and unzipping files inside them, PowerGREP treats ODF files as single document files. If this sounds confusing: PowerGREP simply treats your OpenOffice files the way you expect it to when marking files to be searched through, and when telling PowerGREP to copy or move files around. The whole ODF file will be moved, rather than the XML files inside of it.
By default, PowerGREP uses the IFilter that is included with OpenOffice to extract the text from ODF files. You'll see a plain text representation of your ODF files in PowerGREP. When using the IFilter, PowerGREP cannot modify ODF files because the IFilter system is read-only.
PowerGREP is not capable of displaying formatted text or pages like OpenOffice. Instead, PowerGREP searches through the raw XML content of ODF files. PowerGREP can also search-and-replace through ODF files in this mode. Though all those XML tags may seem to get into your way at first, that extra bit of complexity actually opens up a whole world of possibilities. The XML tags represent your document's formatting. By searching for, removing and inserting the XML tags, you can search for and alter the formatting of your document. To find out which tags to use, simply create a few test documents in OpenOffice using the formatting you want. Navigate inside the ODF files in PowerGREP's File Selector. Right-click on one of the XML files inside it, and select Edit. PowerGREP's editor will show you the raw XML code that PowerGREP searches through.
The IFilter in OpenOffice 3.0 and 3.1 is broken. It cannot be used by PowerGREP, Windows Search, or any other application that uses the IFilter system. You can resolve this by copying the files uwinapi.dll and shlxthdstlport_vc7145.dll from OpenOffice into your c:\Windows folder or by adding the folder that contains these files to the system path.