10/02/81	value_defined, vdf

Syntax:  vdf name {-control_args}


Syntax as active function:  [vdf name {-control_args}]


Function:	 returns true if name has a value set by the value_set (vs)
command or by "value_get -call", false otherwise.	 The value can be
perprocess or reside in a value segment (type "help value_get").


Arguments:
name
   is a character string.  It can be -name STR to specify a name
   beginning with a minus sign, to distinguish it from a control
   argument.


Control arguments:
-pathname PATH, -pn PATH
   specifies a value segment other than the current default one,
   without changing the default.  For more information, see "Notes on
   value segment".
-permanent, -perm
   returns true only if a value is defined in the value segment,
   regardless of whether a perprocess value exists.  The default is to
   return true for either a perprocess or a permanent value.
-perprocess, -pp
   returns true only if a perprocess value is defined.


Access required:
r to the value segment, except for perprocess values.  Lack of r
access is equivalent to no value defined in the segment.


Notes:  See the related command/active functions value_get (vg),
value_set (vs), value_delete (vdl), value_list (vls), value_set_path
(vsp), and value_path (vp).


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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