Co-authoring with Cloud Drive Mapper (CDM)

When using CDM with Microsoft 365 to access OneDrive, SharePoint, and Teams storage locations, multiple users can collaborate simultaneously on Word documents, Excel spreadsheets, and PowerPoint presentations. This collaborative functionality is known as co-authoring.

When you open a Word document, Excel spreadsheet, or PowerPoint presentation from a CDM-mapped drive, Microsoft Office communicates with a Cloud Driver Mapper COM service (CDM.CoAuthHandler.exe). This service provides relevant information from Microsoft 365 to enable co-authoring.

Co-authoring with CDM is on by default for Word, Excel, and PowerPoint files stored in OneDrive, SharePoint, and Teams unless turned off by your system administrator. For more information about deactivating and activating co-authoring for CDM, see Turning co-authoring off or on.

You can verify that co-authoring is enabled if when you open a supported file, AutoSave is turned on. Names of users co-authoring a document appear in the window's top-right corner.

To effectively use co-authoring with CDM, the following requirements are necessary:

Mapping to at least one of the following drive types: Direct: OneDrive, Direct: SharePoint document library, Direct: SharePoint site, Dynamic: OneDrive shortcuts, Dynamic: SharePoint, Dynamic: Microsoft Teams, or Dynamic: Custom.
All co-authors must have permission to access and edit the document.
You must enable AutoSave to save plain text edits in real-time and allow simultaneous viewing of changes by other users with access to the same document.

Only plain text edits are supported in real-time. Other changes, such as images, videos, charts, font color, bold, etc., require waiting for the save to complete. The time taken depends on the size of the changes.

We recommend using the most recent versions of Microsoft 365 apps with CDM. Although you can use co-authoring in some legacy Microsoft Office versions, the older versions may have reduced functionality. For more information about legacy Microsoft Office versions, see Using legacy Microsoft Office versions with CDM.

CDM supports the following Microsoft Office file formats and versions with co-authoring:

Microsoft Office app	Supported file formats	Supported versions
Excel	.xlsx .xlsb xlsm	The most recent version of Excel for Microsoft 365 apps.
PowerPoint	.pptx .ppsx	Microsoft Office 2016 and above.
Word	.docx	Microsoft Office 2016 and above.