DOCM is an older file type used by Microsoft Office in 2007. It is an XML text format that uses ZIP compression to save hard drive space. The DOCM file saves macros and VBA scripts that may be lost if the document converts to other DOC or DOX types. Without the ZIP compression, these files may take forever to download or email to another party. Like other Word documents, the DOCM preserves complex formats, including images, tables, fonts, and colors. You can open DOCM in Microsoft Word versions from 2007 to 2013 or OpenOffice. MobiSystems OfficeSuite Pro 7 can also read these files. Unfortunately, most modern document software programs cannot decipher DOCM.