This tutorial explains how to create and import experiment description or xar (eXperimental ARchive ) files. Xar files contain XML files that describe an experiment as a series of steps performed on specific inputs, producing specific outputs.The topics in this section describe the xar.xml structure and walk through several specific examples. After working through these examples, readers should be able to begin authoring xar.xml files to describe their own experiments. You can author new xar files in an XML editor.