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It was expected that a user would actually want to look up a name in a
sequence of directories (e.g., first a local directory associated with
his current process; second, a directory containing files that live
from session to session and third, a system provided directory
containing generally available subsystems). In order to automate this
procedure, we introduced the idea of a scan list. This was simply an
ordinary C-list in which the capabilities alternated between
directories and access keys. An action was provided by the directory
system which would accept two parameters, a text name and a C-list.
The directory system would assume the C-list was in the form of a scan
list, and look up the text name in the successive directories
contained in the C-list, and check against the associated access keys.
An error was returned if the directory system did not find a
capability for a directory or access key when appropriate.