Appendix I A Glossary of Terms

doc id

A tumbler assigned to a document upon its creation which corresponds to its virtual stream address.

doc-range

A virtual stream region containing several documents defined by a span. A doc-range is like a span, except that it specifies a "span" of documents rather than a span of text or links within a document. Like a span, it consists of a stream address and a width.

end-set

Any of an indefinite number of terminii (defined by tumbler addresses) a link may have on the virtual stream. Examples include from-sets and to-sets, formally equivalent specifications distinguished only by the directionality desired and implemented by their creator. The creator is not neccesarily the "owner" of the document in question.

from-set

The specification of the endpoint of a link from which the link was initially defined. In the present minimal frontend the position of a from-set in the display of the document is indicated by reverse video text.

link id

A tumbler assigned to a link upon its creation which corresponds to its virtual stream address.

home-set

The specification of the document or spans with which the link is stored; an indication of the creator of the link. The home-set of a link is not necessarily the same as that of either its from-set or its to-set.

span

A pair of tumblers, a starting stream address and a width, that define a region of the virtual stream. A span has two parts: a stream address and a width. A span can describe any contiguous region of the virtual stream. Typically, the only instance of a span being used outside of a v-spec is in a doc-range.

span set

A list of spans. In the current implementation span set starts with an integer indicating the size of the set, followed by a string of spans.

spec set

A list of doc-range and vspecs. The most common form of address specification that the system requests accept is the "spec set," short for specification set. In the backend/frontend interface, a spec set starts with an integer indicating the number of specs in the spec set, followed by a string of specs.

spec

Either a doc-range or vspec. A spec consists of a document id or link id, and a span set. All spans in the span set refer to the document or link in the spec.

stream address

A tumbler which corresponds to an address in the virtual stream.

to-set

The specification of the endpoint of a link to which the link was initially created. In the present minimal frontend the position of a to-set in the displayed document is indicated by underlining.

tumbler

The type of ordinal number used in the system for stream addresses. See appendix 2.

virtual stream

All the data on the system -- text, links, etc.-- conceived as one extended list of bytes.

virtual stream address or vsa

position of the thing -- document, link or character -- on the virtual stream.

v-span set

A span set within a v-spec. A v-span set can only describe spans within the document of the v-spec.

v-span

A v-span has two parts, like a span: a stream address, and a width. The stream address is not the entire tumbler address of the span in question, but only the part which is local to the document or link. For example, if the stream address is the first character of a document where the full address would be, say, 17.0.23.0.42.0.1.1, the span's stream address would be simply 1.1, the rest is already known from the context of the spec. The width is also a tumbler. If you want to retrieve 500 characters, the width would be 0.500; if you wanted the entire text of the document, the width would be 1. This is because the span's width added to the stream address is the address of the first thing NOT to include. Starting at 1.1 with a width of 0.500 means that everything up to and not including 1.501 is specified. With a width of 1, the first non-included item would be 2.1, the first link.

v-spec

A doc id followed by a spanset

width

the size of a region; the sum of the origin and width address is the first thing past the end of the region.