This dialog box has several uses within the Environment Manager.
    In general, it is used to specify and manipulate lists of
    directories or file specifications.

    Enter a string into the Library/String field and click on
    either of the Append or Add Before Selected buttons to add the
    string in the appropriate place in the Library/String List
    field. The Library/String List field contains a list of
    strings, one string per line.

    Delete items from the Library/String list by selecting  the
    appropriate item(s) in the Library/String List field and
    clicking on the Delete Selected button. The OK button accepts
    the Library/String List and dismisses the dialog box. The
    Cancel button dismisses the dialog box without changing the
    Library/String.

    In some cases a Select... button appears to the right of the
    Library/String field.  If present it may be used to browse.

    When more than one item is shown in the Library/String List,
    up and down-arrow buttons are displayed to move the selected
    item up or down in the list.