Enter the MIME type for the file extension, or leave empty to omit the MIME type association. If you do specify a MIME type you should also create a separate MIME Type registration, unless the MIME type is a standard type that is preregistered on the target system.
Select the perceived type of the file extension from the drop-down list, or enter your own type. Windows XP and later use the perceived type as a kind of generic file type to provide common shell functionality to classes of files, instead of individual file types.
The drop-down list contains the generic types that are predefined by Windows XP, but you are free to enter your own. In that case, you may want to add the new type to the HKCR\SystemFileAssociations registry key; use the Registry Keys and Values project page to do so. Consult the Microsoft Windows Platform SDK documentation for more information about perceived type registration.
Tip: If you do not want to register a perceived type for the file extension, then clear this field.
The Perceived attribute is not supported by Windows Installer.