DXF, Drawing Interchange Format, or Drawing Exchange Format, is a tagged data representation of AutoCAD drawing file. Each element in the file has a prefix integer number called a group code. This group code actually represents the element that follows and indicates the meaning of a data element for a given object type. DXF makes it possible to represent almost all user-specified information in a drawing file.
Files with .OTP extension represent presentation template files created by applications in OASIS OpenDocument standard format. The contents of such a file include presentation information in the form of slides with text, images, shapes, multimedia content, transition effects and other slide elements. These template files are used for creating new presentations quickly based on the styling information stored in the template itself. OTP files can be created and saved with several different applications such as Impress that comes with OpenOffice suite and Microsoft PowerPoint. The OTP file format is similar to Microsoft PowerPoint template files .POT and .POTX.
You can also convert DXF into many other file formats. Please see the complete list below.