Scan lists

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.