DOC, short for document, is a term that can be confusing. It is used to identify Microsoft Word Documents because they use a .doc extension and it is also used to identify an eBook format originally used on PalmOS devices by Aportis and called variously DOC, Aportis DOC, and most recently PalmDoc or PalmDOC. PalmDOC files are sometimes called PDB files as this is the extension they normally have.
Microsoft Word DOC files
When DOC is used to refer to Microsoft Documents is can refer to any of several versions of .doc files from the original DOS files to Word 2003 files. (The native format for Word 2007 is Microsoft Office XML, DOCX). There is no guarantee that a product that claims to read DOC files will be able read any particular version of doc file or support all of the features of that version.
To aid in the exchange of doc files between programs every Word version since Word 97 has been able to save their doc files in a Word 97 format. Saving a Word file in this format will lose any of the database features that were added to the file format after Word 97.
There are many other word processing programs that can read and write files that are .doc compatible however some of the .doc features may or may not be supported. This can cause problems when trying to read a .doc file with one of these programs. In addition the eBook translation programs will not look for one of these programs to aid in the translation. The main work around is to use RTF files as source documents. This format is designed to allow the exchange of documents between different programs and operating systems. All Word programs can save files in RTF format.
Word is also considered part of the suite called Microsoft Office files.