/Mount-Wim /WimFile: {/Index: | /Name: } /MountDir: /readonly Mounts the WIM file to the specified directory so that it is ...

/Mount-Wim /WimFile:
  {/Index: | /Name:}
  /MountDir: [/readonly]

  Mounts the WIM file to the specified directory so that it is available for 
  servicing. /ReadOnly sets the mounted image with read-only permissions.
     
    Examples:
      DISM.exe /Mount-Wim /WimFile:C:	est\images\myimage.wim /index:1 
        /MountDir:C:	est\offline

      DISM.exe /Mount-Wim /WimFile:C:	est\images\myimage.wim /index:1 
        /MountDir:C:	est\offline /ReadOnly