1 The user should be provided with facilities to define
the type of external files.
1.2 Each external file type may have an
associated tool which may be applied to the file.
1.3 Each external file type may be represented as a specific icon on
the user ’s display.
1.4 Facilities should be provided for the icon representing an external
file type to be defined by the user.
1.5 When a user selects an icon representing an external file, the
effect of that selection is to apply the tool associated with the
type of the external file to the file represented by the selected