07/14/87  Entrynames (general information)

Entrynames are the names of objects used in the Multics filesystem,
such as directories, segments and links.  An object of this sort must
have at least one name, but may have many names, all of which reside in
the same containing directory.


Entrynames may be from 1 to 32 characters long, and must contain at
least one character which is not an ASCII space.  All of the characters
must be ASCII characters, from 000 to 177 octal, and the greater-than
character (">") is forbidden.  The greater-than character is used to
construct pathnames.


There are a number of other restrictions on entrynames which are
enforced by different parts of the system.  Because they are not
enforced by the filesystem itself, it is sometimes possible to violate
them, but it is not recommended.  The -name control argument to the
delete, delete_name and rename commands was provided to permit dealing
with illegal names.  Most of the restrictions reserve characters for
one purpose or another.  There is no way to protect these characters
from evaluation in contexts which implement the features for which they
are reserved.


List of restrictions on entrynames:

1.  Entrynames should not contain null components.  Components are
    parts of names delimited by periods (".").  For example,
    "example.pl1" has two components, "example" and "pl1".  The last
    component, or suffix often indicates the type of file which it
    names.  A null component is a component of zero length, which would
    occur in a name which begins or ends with a period, or which
    contains two adjacent periods ("..").


2.  Entrynames should not contain less-than characters ("<").  The
    less-than character is used to construct relative pathnames.

3.  Entrynames should not contain two consecutive colons ("::").  This
    compound delimiter is used to construct archive component
    pathnames, which permit reading an archive component without
    extracting it from the archive.

4.  Entrynames should not contain asterisk ("*") or question mark ("?")
    characters.  These characters are used by the star convention,
    which is used to select entrynames by wildcard matching.


5.  Entrynames should not contain the equal ("=") or percent ("%")
    characters.  These characters are used by the equal convention,
    which is used to construct entrynames when a command takes several
    arguments, particularly when the first argument can be a starname
    so that matching names can be derived, but also as a typing aid.

6.  Entrynames should not contain the dollar ("$") or vertical-bar
    ("|") characters.  These characters are used to construct virtual
    pointers and virtual entry values.  These "virtual" values are the
    printable representations of Multics pointer and entry constants.

7). Entrynames should not begin with a hyphen (-).  Many of the Multics
    commands will interpret entrynames which start with hyphens to be
    control arguments.


Notes: Please refer to the following info segments for additional
information:
  pathname.gi.info
  archive_convention.gi.info
  starname.gi.info
  equalname.gi.info
  virtual_pointer.gi.info
  virtual_entry.gi.info


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Historical Background

This edition of the Multics software materials and documentation is provided and donated
to Massachusetts Institute of Technology by Group BULL including BULL HN Information Systems Inc. 
as a contribution to computer science knowledge.  
This donation is made also to give evidence of the common contributions of Massachusetts Institute of Technology,
Bell Laboratories, General Electric, Honeywell Information Systems Inc., Honeywell BULL Inc., Groupe BULL
and BULL HN Information Systems Inc. to the development of this operating system. 
Multics development was initiated by Massachusetts Institute of Technology Project MAC (1963-1970),
renamed the MIT Laboratory for Computer Science and Artificial Intelligence in the mid 1970s, under the leadership
of Professor Fernando Jose Corbato. Users consider that Multics provided the best software architecture 
for managing computer hardware properly and for executing programs. Many subsequent operating systems 
incorporated Multics principles.
Multics was distributed in 1975 to 2000 by Group Bull in Europe , and in the U.S. by Bull HN Information Systems Inc., 
as successor in interest by change in name only to Honeywell Bull Inc. and Honeywell Information Systems Inc. .

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Permission to use, copy, modify, and distribute these programs and their documentation for any purpose and without
fee is hereby granted,provided that the below copyright notice and historical background appear in all copies
and that both the copyright notice and historical background and this permission notice appear in supporting
documentation, and that the names of MIT, HIS, BULL or BULL HN not be used in advertising or publicity pertaining
to distribution of the programs without specific prior written permission.
    Copyright 1972 by Massachusetts Institute of Technology and Honeywell Information Systems Inc.
    Copyright 2006 by BULL HN Information Systems Inc.
    Copyright 2006 by Bull SAS
    All Rights Reserved