GZigZag Glossary

$Id: gl.wml,v 1.4 2001/05/23 14:56:01 tjl Exp $
Tuomas Lukka

This is a short glossary of terminology related to GZigZag. Only a short definition of each term is given, possibly with a reference to more material on the subject.

Note that this document contains some formatting that is best rendered using a true CSS1 standard-compliant browser such as Mozilla; however, it should work reasonably well with any browser that can at least ignore CSS that it doesn't understand. Unfortunately, Netscape Navigator 4.7, for example, doesn't. Well, that's life...

A non-CSS version exists: you can try by compiling this document from its WML version with some switches.. (if you came here through the WWW, there should be an alternate link on the referring page. However, I like the pretty rendering by Mozilla so much that that's still the default.

ZigZag structure / space
A simple structure, based on cells and dimensions which the user is able to easily shape into any desired structure. All interrelated pieces of information can be close to each other on some dimension.
The smallest unit of information in ZigZag. A cell can contain a text string or a single span in a permascroll; the separation is because a text string can be edited but a span can only be lengthened or shortened: no characters can be inserted. Cells are connected to each other along dimensions.
Connecting cells along dimensions is what ZigZag is about. Locally, dimensions work just like on a spreadsheet: each cell can be connected to one cell in the positive direction and to one cell in the negative direction along each dimension. However, there are no global constraints between the dimensions.
The negend of a rank, or, for circular ranks, a specially designated cell. If a rank of cells has one "special" cell, then it is usually the headcell.
Cells that are connected along a dimension are called each other's neighbours. Often, the term posward or negward is used with this term as in "the negward neighbour on d.cursor".
In the positive/negative direction along a rank.
As far as you can go negwards or poswards. Circular ranks have no ends.
A rank on a dimension D is simply a set of cells that are connected to each other on D. A given cell can only be on one rank on a given dimension.
A set of cells selected from the structure by a set of rules, for visualization. For example, the row and column raster select, starting from the cursor, a single rank in one dimension an all ranks in another dimensions that intersect that rank. The raster for the vanishing view selects all cells within a given radius of the cursor.
relcell, or relation cell
A cell which exists not for its content but for expressing a relationship between other cells. For example, the cell between a father and mother in the family tree demo is a relcell.
A rank which loops. Ringranks still do have a specific headcell, specified somehow.
These words simply correspond to ranks being viewed horizontally/vertically. They do not mean anything in the abstract structure, but only in the visualizations.
A way of placing the cells in a particular raster on the screen.

Ted Nelson's design built on top of ZigZag structure, based on flobs.
A multi-dimensional flying object. That is, an entity representing something that may have any number of flob coordinates. For example, an email's sender is one flob coordinate, its subject another.

A hypertext system, finished in 1988, which works by stable fluid media content instead of URL-like pointers.
fluid media
Any media types that can be subdivided. Text, audio, video, images.
A storage philosophy for fluid media where each smallest unit (e.g. character of text) is assigned a permanent identifier when it first enters the system. Of course, references to the smallest units usually happen through spans for efficiency.
A (reference to a) contiguous section of the permascroll.
A list of spans that describe a virtual stream of fluid media. A "document" or one version of a document. Modifying a document does not modify the permascroll, except by appending new inserted characters. Instead, the spans of the vstream are modified: split apart, new spans inserted etc.
The inclusion of the same material in a permascroll in two different documents. One of the fundamentals of the Xanadu88 model is that it is efficient to search for transclusions of a given span.
transpointing windows
Windows on a computer screen that show the connections or transclusions between each other.
A copyright scheme where the copyright holder grants the public a permission to refer to any portion of a given document and publishes the document in a permanent location. This way, anyone can quote the document by referring to it and the reader's browser will then go to the originator's server for the original material so that a micropayment can be made to the original author of the material.