To research these issues, I have sought an abstract design which can simultaneously satisfy these various constraints, hoping in the process to uncover tradeoffs and solution pieces. The result is a design called LinkText, which this paper will briefly summarize. (For more info, ask for "Toward Hypertext Publishing, Issues and Choices in Database Design") LinkText is divided into seven levels of expressiveness: content, mail, references, links, objects, sensors, and assistants. Lower levels can exist without higher ones, but true hypertext is present only at the links level and above.
CONTENT At the lowest level, published works are like cassette tapes -- little bags of content which one can copy and give to friends. Format standards make content understandable, cryptographic signatures prevent forgery, and one has a free speech right to distribute any expressible content.
MAIL There are various "places" (typically a single machine) which a published work can be "at", and an underlying mail system allows one to send a work to or request a work from a place. (Places and works both have globally unique names.) One typically obtains a work from a public distributor, who is then required to send the author his/her requested royalty price. Since distributors are public, copyright can be enforced by undercover police audits. The unit of purchase is one person's access to a work at a place, for which one pays royalties plus a local markup. (Connect time and CPU usage are paid for separately.) Mail support for anonymous pseudonyms allows one to read and publish anonymously. Privacy of who reads what is also supported by digital "cash" and the fact that all published works can be read by anyone for the same royalty price.
REFERENCES One work can reference another work by containing the name of the referenced work. To both reduce the distributed update problem and avoid criticism being made to look stupid by subsequent changes in the work criticized, works cannot be changed once published. One can, however, indicate an intention to reference the author's most recent version of a work with a "latest-version" reference "wrapper".
To support local (within a place) reference following, each place has an index mapping each locally mentioned name onto either a locally contained work, or a "stub" which can have hints about other places to look. For reliable global (across all places) reference following, each work has imbedded in its name the name of the "home" where it was first published, which should have a copy of the work if any place does. A design option is to require the home copy to be permanent (ensured by the home's posting of a bond).
LINKS If a reference can be as easily "backfollowed" as followed, then it is a "link". At the links level all references are "links", and so a general "right to respond" exists allowing anyone to create a criticism of a work which can be found directly from the criticized work. This helps solid criticism to sink popular but bogus ideas, and supports reader filtering based on easily found evaluations. A non-reference link can also be created between two existing works; such a link has three references, going to a from-end, a to-end, and a link type. (Virtually, all links have these references.)
To allow one to read the evaluations on a work before buying it, backfollowing a reference (unlike following) is free of royalty charges. To make backfollowing feasible locally, each place manages a "backreference" table mapping names of contained works and stubs onto sets of all names of contained works it is referenced by (indexed by link type). For reliable global backfollowing, the author of a work must pay to put a (optionally permanent) copy of that work in the homes of all works it references. Thus a work's home will tend to accumulate all works referencing it.
Each work stored at a place has a "funder" who pays the storage cost and is paid a markup on the royalty charges. To further support a right to respond, public distributors act as common carriers, allowing anyone to fund any work, with fees and service blind to content. (The first to volunteer for a given time interval wins any conflict.) Also, all homes must also be indefinitely expandable. Thus one can place a criticism "next to" any work at any public place. No way is provided, however, for a critic to find all public copies of a work to respond to, as such a method might be used to erase a "subversive" work.
OBJECTS At the object level, the content of a work, including text and graphics, is broken up into a tree of small objects connected together by links. (Text built from links -- LinkText!) This uniform representation allows great expressiveness; all objects (including links) are directly referenceable. One can reference paragraphs, sentences, words, or even a word concept which specifies both a character sequence and a meaning. Alternative versions can directly "reuse" chunks of text. (To disambiguate the intended context of a referenced text chunk, use an "in-context" wrapper.) Backfollowing references to individual words allows efficient (and global!) keyword searching.
Even though they are broken into small objects, works remain as units of bookkeeping and context. All objects in a work are published at the same time by the same author, and are sold as a unit for one price (except for free pieces). Works are atoms of context; either all or none of a work is at a place, with the following exception. Instead of sending a copy of a work to the home of a referenced object, one might only have to send the referencing object (plus its references) or nothing at all, if there are already a lot of certain references to the same object. To make it easier to track down plagiarism, one must reuse an object with a given set of references, rather than make a copy of it.
SENSORS A general pattern language can check that conditions are met. When used in a data driven mode, patterns can notify one about new published items of interest. When used in a goal driven mode, patterns can check that semantic constraints are met. To avoid a conflict between enforcing such constraints and total free speech, objects that fail to meet the constraints of their one type are flagged as "unusual" (with an unusual link), but still allowed. Readers who wish can filter out unusual objects.
ASSISTANTS If one had a computational agent running "at" a place, it could do some cheap filtering before sending items across expensive communication lines.
The LinkText design preserves rights and global reliability by adding various responsibilities, and in so doing highlights important tradeoffs in hypertext publishing.