Tumblers
Encyclopedia
In the design of the Xanadu computer system
, a tumbler is an address of any range of content or link or a set of ranges or links. Tumblers were proposed by Ted Nelson
in his book Literary Machines
. They were used in the Xanadu FEBE (Front End - Back End) protocol in a manner similar to the use of URIs between web browsers and servers.
A tumbler is a unique numerical address of any interesting artifact. It resembles an IP address
, but is much larger and has much more detailed structure. The structure looks like this.
1. < node >.0. < user >.0. < document >.0. < element >
The "1." is used in order to mark the start of a new address. The individual fields of the address are divided with ".0." so that they can be arbitrarily long. Each < element > has the format "n. n. ... . n", a hierarchy of subaddresses.
The last element denotes the type of data the tumbler refers to, for example:
1. Text/Bytes
2. Links
3. Bitmaps
4. etc.
The 9287th byte of this version of the document would be 1.2368.792.6.0.6974.383.1988.352.0.75.2.0.1.9287 and the 356th link would be 0.2.356 on the end instead.
A tumbler can be issued only once and never changes. The type of structure can grow at will, so the address space is infinite.
Nelson also introduces the concepts of direction and a "span", which is a part of a document that is semantically meaningful for the document. For example, one can speak of "2 chapters back" or "300 bytes forward".
Project Xanadu
Project Xanadu was the first hypertext project, founded in 1960 by Ted Nelson. Administrators of Project Xanadu have declared it an improvement over the World Wide Web, with mission statement: "Today's popular software simulates paper...
, a tumbler is an address of any range of content or link or a set of ranges or links. Tumblers were proposed by Ted Nelson
Ted Nelson
Theodor Holm Nelson is an American sociologist, philosopher, and pioneer of information technology. He coined the terms "hypertext" and "hypermedia" in 1963 and published it in 1965...
in his book Literary Machines
Literary Machines
Literary Machines is a book first published in 1980 by Ted Nelson, and republished 9 times by 1993. It offers an extensive overview of Nelson's term "hypertext" as well as Nelson's Project Xanadu...
. They were used in the Xanadu FEBE (Front End - Back End) protocol in a manner similar to the use of URIs between web browsers and servers.
A tumbler is a unique numerical address of any interesting artifact. It resembles an IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
, but is much larger and has much more detailed structure. The structure looks like this.
1. < node >.0. < user >.0. < document >.0. < element >
The "1." is used in order to mark the start of a new address. The individual fields of the address are divided with ".0." so that they can be arbitrarily long. Each < element > has the format "n. n. ... . n", a hierarchy of subaddresses.
The last element denotes the type of data the tumbler refers to, for example:
1. Text/Bytes
2. Links
3. Bitmaps
4. etc.
| Address area | Tumbler Address | Comment |
|---|---|---|
| Node | 1.2368.792.6 | This is the computer with the number 2368.792.6 |
| User | 1.2368.792.6.0.6974.383.1988.352 | This is user 6974.383.1988.352 on the above computer. |
| Document | 1.2368.792.6.0.6974.383.1988.352.0.75 | The user's document number 75. |
| Version | 1.2368.792.6.0.6974.383.1988.352.0.75.2 | Version 2 of the document. |
The 9287th byte of this version of the document would be 1.2368.792.6.0.6974.383.1988.352.0.75.2.0.1.9287 and the 356th link would be 0.2.356 on the end instead.
A tumbler can be issued only once and never changes. The type of structure can grow at will, so the address space is infinite.
Nelson also introduces the concepts of direction and a "span", which is a part of a document that is semantically meaningful for the document. For example, one can speak of "2 chapters back" or "300 bytes forward".
See also
- Purple NumbersPurple NumbersPurple Numbers is a suite of tools that allows one to address paragraphs of HTML content. It was originally conceived by Douglas Engelbart for his creation of hypertext. The concept was later implemented in PurpleWiki by Eugene Eric Kim and Chris Dent. The name comes from the faint, purple numbers...
, a proposal to address paragraphs in Web pages. - XPointerXPointerXPointer is a system for addressing components of XML based internet media.XPointer is divided among four specifications: a "framework" which forms the basis for identifying XML fragments, a positional element addressing scheme, a scheme for namespaces, and a scheme for XPath-based addressing...
- Cross-referenceCross-referenceA cross-reference is an instance within a document which refers to related or synonymous information elsewhere, usually within the same work. To cross-reference or to cross-refer is to make such connections. The term "cross-reference" is often abbreviated as x-ref, xref, or, in computer science,...