All reference documents are included in the SmartOpen help file
Extensions are the highest level object in SmartOpen. They appear leftmost in the Display Box, and do not have any parent objects. Their direct child objects are Conditions. They have only one property, which is their extension. This can be an existing extension, such as .txt, a new extension created by SmartOpen, or a special case extension. There are two special case extensions, Unknown and All. The Unknown extension refers to all currently unassociated (by windows) extension, and the All extension refers to all extensions, associated and Unknown. It is not recommended to use the All special case extension, as this would cause all files to be opened with SmartOpen, however, it is provided for completeness.
To add an extension, double click on the [Add New Extension] item in the Display Box, or select any existing extension or the [Add New Extension] item, and click the Add Button. There is only one property to be set for an extension object, and that is its extension. If this is not one of the two special cases a . will be added to the front of any extension entered if there is not one already, so txt will become .txt, whereas .doc remains unchanged.
To expand an extension to view the conditions associated with it, click the + sign next to it, or double click it.
To remove an extension select it and press the Delete Button, or the Del key on the keyboard.