version. InDesign processes the markup and regenerates the document.
Once opened, immediately go to File > Save As and save it as a native InDesign document ( .indd ). This converts the IDML link into an editable file for your specific version. how to convert indesign file to older version link
"I can't open this! My computer says the file is from a newer version of InDesign." The client is still using InDesign CS6 version
after opening the IDML in the older version to create a new .indd file. immediately go to File >