Copy Control (draft-daviel-web-copy-control-00.txt)


This describes a simple HTTP header syntax (or HTML META tag) to
define the copyright status of a document in a machine-readable way,
and provide a link to a reference document which would define
the status explicitly.

The purpose of this proposed header is twofold.
1. To make it easier to design agents that may create compilations
of existing work automatically, or to search for only copyright-free
2. To make it clear to consumers (via a popup, for instance)
that certain material is copyright when they perform actions such
as printing or saving a page.

There is not intention to provide a mechanism for document signatures,
modification control, etc.

This work was in part prompted by a pamphlet on copyright
issues for schools which included a note "Don't print anything from the 

Briefly, one includes a header or META tag such as
Copy-Control: v 1.0 p 1 s 1 q 2 u
<META HTTP-EQUIV="Copy-Control" CONTENT="v 1.0 p 2 s 2 q 2">
where the values for p(rint), s(ave), q(uote) are given
0 = forbidden, 1 = conditional, 2 = allowed.

"quote" means to copy a portion of a document, is meant to reflect 
the common usage in printed material (for purposes of review, etc.),
and might be checked by a clipboard function.
The URL (required for level = 1 "conditional") fully defines the
conditions, copyright holder, etc. (in human-readable form).

This does not address saving of documents by search engines (addressed
by the "ROBOTS" META tag and /robots.txt file), or saving
of documents in cache (addressed by the "Expires" header and HTTP 1.1
extensions). It does not enforce copyright control, since it is easily
circumvented. It merely provides notification. The syntax is a 
compromise between a rigorous definition useful for agents,
and a form that is simple enough to write by hand.

Possible revision (thought of since the original submission):
define a numeric limit below which permission need not be sought, viz.

Copy-Control: v 1.0 p(25) 2 s(1) 2 q 2

which states that 25 copies of a document may be printed without permission.
This feature would be used by search agents, for example a teacher
looking for an article about Mars rovers which could be printed out
for a class.

Why can't the existing &copy; tag be used ? Obviously, this header
doesn't replace that, since the header or META tag is invisible to
the user. Firstly, the usual copyright notices are small and at the
end of a document (whereas the notices on videotape are usually large
and at the beginning ..), and secondly, since there is no defined
format it is difficult for agents to interpret the tag (which might
be in the body of text and referring to some other document, for

Andrew Daviel  : home of multisearch, META generator etc.

Received on Friday, 22 November 1996 10:46:25 UTC