ASSOC [.ext[=[fileType]]]

.ext

Specifies the file extension to associate the file type with

fileType

Specifies the file type to associate with the file extension

Type ASSOC without parameters to display the current file associations. If ASSOC is invoked with just a file extension, it displays the current file association for that file extension. Specify nothing for the file type and the command will delete the association for the file extension.