An ICML file is a document created by InCopy, a professional writing and editing program. It contains document text, graphics, and page layout settings. ICML files may also be used to link portions of an Adobe InDesign document (.INDD file) using a network fileserver.

ICML file open in Adobe InCopy 2020 InDesign users can link a subset of an INDD file to one or more ICML files and grant editing permissions to them using an .ICMA assignment file. Once the ICML files are edited, the InDesign document can be automatically updated with the new content. Users typically do not directly open ICML files that are linked to an ICMA assignment file. When users "edit" an ICMA assignment file, they are actually modifying ICML files behind the scenes using InCopy. NOTE: ICML files are used by InDesign and InCopy CS4 and later. The CS3 version used the .INCX extension.