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- From: Paul Prescod <email@example.com>
- To: xml-dev <firstname.lastname@example.org>
- Date: Mon, 31 May 1999 14:31:34 -0500
Rough draft. Comments appreciated. Note that getting a number-identified
URN namespace is easier and faster than getting a name-identified one so
that is the best first step. Someone more ambitious (thanks for
volunteering, David) could start a standards-track process towards getting
a name-identified one.
This is an application for a URN namespace based on time-qualified email
addresses for abstract objects. It is prompted by the rampant abuse of
URLs as names for XML namespaces and as the names for other abstract,
Registration version number: 1
Registration date: 1999-0?-??
Declared registrant of the namespace:
ISOGEN International Corp.
Declaration of structure:
The identifier structure is as follows:
urn:urn-<assigned number>:<addr-spec>:<date> [ : <qualifier> ]
The addr-spec syntax is defined in RFC822.
The date production is defined by ISO 8601 as the "recommended
primary notation" and must specify a year, month and day.
A date/addr-spec pair is called a time-qualified mailbox address
The person, organization or group of people that owns the
addressed conceptual mailbox (see RFC822) on that date are
known as the address owners. Alternately, the person,
organization, or group that owns or owned the domain on
the date could assign control of TQM address without actually
setting up a mailbox.
If ownership of the email address or entire domain is transferred
during a particular day then no affected TQM address is legal
The structure of the optional qualifier portion is defined by each
address owner within the constraints defined by RFC 2141. They might
sub-delegate responsibility by defining some substructure in the
qualifier. Address owners are recommended that they are ultimately
responsible for the persistence of their entire namespace. They
might use additional time qualifiers to help ensure this.
Relevant ancillary documentation:
ISO 8601 defines the date syntax used.
IETF RFC822 defines the mailbox syntax used.
Identifier uniqueness considerations:
The basic functioning of Internet email depends upon email addresses
being globally unique at any particular time.
Identifier persistence considerations:
Persistence of the URNs in this namespace is independent of the
mutability of the underlying documents. A URN once assigned will
never be reassigned to a different resource; the assignment is
persistent and immutable. Responsibility for ensuring name
immutability is delegated to the address owners.
Process of identifier assignment:
The process of email address assignment varies from domain to domain
but RFC822 guarantees that every address maps to a single conceptual
mailbox. The person, organization or group responsible for that
group is responsible for the namespace rooted at that mailbox.
Process of identifier resolution:
At this time there is no defined resolution mechanism. For the
intended set of resources this is not a problem because they
are abstract and not retrievable. It might be possible to use
the email address to ask for information about the abstract
object but the recipient is not guaranteed to be responsive.
Rules for Lexical Equivalence:
The case sensitivity of dates and addr-specs are defined in their
The qualifiers are defined to be be case sensitive but a TQM
address owner might assign all of the qualifier case variations
of a URN to the same resource. They could mandate this definition
namespace-wide in which case that namespace would be effectively
Conformance with URN Syntax:
There are no additional characters reserved.
Paul Prescod - ISOGEN Consulting Engineer speaking for only himself
Alabama's constitution is 100 years old, 300 pages long and has more than
600 amendments. Highlights include "Amendment 393: Amendment of Amendment
No. 351", "Validation of Laws Regulating Court Costs in Randolph County",
"Miscegenation laws", "Bingo Games in Russell County", "Suppression
of dueling". - http://www.legislature.state.al.us/ALISHome.html
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