MSW:Stability

1. Stability
SignWriting is the universal script for writing any sign language. Sign languages are human languages based on visual gestures. Sign languages have proven to have many of the uses and benefits of other voiced and written languages, as well as other uses and benefits unique to sign language alone.

Modern SignWriting is a faithful encoding of SignWriting that is stable by design. It is based on the glass-box idea where all necessary information is available to understand input, processing, and output. We can faithfully predict the results of any processing without having to use a computer. The algorithms have been optimized for flexibility, accuracy, simplicity, and speed.

1.A. Semantic Versioning
Modern SignWriting follows the rules for Semantic Versioning v2 (semver.org) and uses a version string to communicate compatibility using three numbers: major, minor, patch. The version string for this document is v1.0.0. It is the first major version. Any string written according to this specification will always be understood by a v1 implementation. The minor version number is second in the version string. It represents an improvement that is compatible for all versions with the same major version and a lower minor version number. This document is the foundation for major version l and will be compatible with all improvements and fixes for major version 1.

1.B. Formal Words
A formal word requires a sequential string of characters. Each encoding in this document is based on the idea of a formal word as an abstract structure. For SignWriting plain text, there are 3 types of words: signbox, term, or punctuation.

The signbox is the 2-dimensional representation of a sign that uses symbols from the ISWA 2010. This 2-dimensional order is represented as a list of symbols with 2 numbers per symbol for coordinate positioning. The 1-dimensional order of the string for a signbox is sequential and will resolve issues of overlap. Beyond that, the sequential order of a signbox should be considered meaningful to the user and should not be modified.

A term is a signbox with an added prefix as a sequential list of symbols. The majority of signs do not use the term prefix. Collation is possible with terms using a binary string comparison. A list of plain signboxes can be sorted using approximate string matching for terms and prepending the term prefix from the exact or closest match found for the signbox.

A punctuation is an isolated symbol used to structure sentences.

1.C. Normal Strings
A normal string is predictable and common. For SignWriting, normal strings do not exist outside of a community of writers. Different editors will often produce different strings for the same sign. Normalization is only possible based on an agreement within a community. Normal strings are only possible when written against a dictionary, otherwise the inherent variability of the mathematical model will produce strings that are approximately equal or equivalent, but rarely the same.

1.D.1. Grapheme, Symbol, and Glyph
For SignWriting, a grapheme is a written mark that corresponds to a part of a meaningful visual gesture. Graphemes are the smallest semantic units capable of causing a contrast in meaning. Many graphemes of SignWriting are visually iconic. When written by hand, the variety and style of graphemes is potentially unlimited. Graphemes are somewhat abstract and do not have a concrete visual form. There are 3 types of graphemes: writing, detailed location, and punctuation.

The writing graphemes of SignWriting represent a visual conception: either hands, movement, dynamics, timing, head, face, trunk, or limb. The body concept is a combination of trunk and limb. The writing graphemes are used in 2 dimensional clusters to create one or more morphemes: the smallest semantically meaningful units in a language. The graphemes do not change size or shape when combined in a visual pattern. The graphemes can overlap and obscure graphemes underneath.

Detailed location graphemes are used individually or sequentially. They represent isolated analysis that is written outside the 2 dimensional cluster.

Punctuation graphemes are used when writing sentences. They are used individually, between 2 dimensional clusters.

For SignWriting, a symbol is equivalent to a grapheme, part of a grapheme, or several graphemes combined. Each symbol has a normative name, a definitive visual representation, and an international agreed upon meaning. The symbols of SignWriting are restricted in size and general shape more so than for other scripts because of 2 dimensional placement and the relations between the symbols. The symbols of SignWriting do not morph or rotate, but can often be changed from one symbol to another through several possible transformations. The specific size and shape of each symbol is designed to balance and complement the other symbols.

The symbols of the ISWA 2010 are extensive and specifically organized for written sign language and sign gestures. The symbol set does not include the specific symbols of DanceWriting or the general symbols of MovementWriting.

Glyphs are concrete representations of the individual symbols. A glyph is a graphic image that provides the appearance or form for a symbol. Most often, the term glyph will corresponds to an image in a font. The glyphs of SignWriting are restricted in size and shape with their corresponding symbols.

The glyphs have two aspects: positive and negative space. All glyphs have positive space: the outline or line of the glyph. Some glyphs have negative space, referred to as the fill of the glyph. When one glyph overlaps another glyph, the negative space of the top glyph will neutralize the positive space of the glyph underneath so that the line of the glyph underneath is partially obscured by the overlap.

1.D.2. Cluster, Sign, and SignBox
For SignWriting, a cluster is a 2 dimensional arrangement of graphemes, glyphs, or symbols. A 2 dimensional cluster of graphemes can be called a graphogram, which should not be confused with a “grapheme cluster” - a technical Unicode term. Likewise, a 2 dimensional cluster of glyphs can be called a glyphogram. A cluster can represents a sign of a sign language or a visual performance of a sign gesture. Many clusters are visually iconic.

A sign is an over loaded term. It can refer to either the visual gesture produced by a real person or the written 2 dimensional representation of that sign.

A signbox is a 2 dimensional mathematical construct with a visual image of variable height and width. The size of a signbox is defined by the cluster of symbols used within the signbox. The border of each signbox is a tight bounding box as the smallest possible rectangle that encloses the set of symbols. The center of a signbox is explicitly defined, either by algorithm or user choice.

1.D.3. Viewpoints, Planes, and Perspectives
Writing based on vision uses two viewpoints: receptive and expressive. The receptive viewpoint is based on the idea of receiving an image. For the receptive viewpoint, the right hand of a signer will be written on the left side of the image. When SignWriting is used for transcription, the receptive view is most often used. The related writing systems of DanceWriting and MovementWriting normally use the receptive viewpoint.

The expressive viewpoint is based on the idea of expressing a concept. For the expressive viewpoint, the right hand of a signer will be written on the right side of the image. When SignWriting is used for authorship, the expressive view is most often used.

The are two main writing planes: the front wall (Frontal Plane) and the floor (Transverse Plane). The choice of writing plane determines the shape of the symbols, such as the fill pattern for the hands or the tail for the movement arrows.

There are two perspectives: front and top. The front perspective is a straight on view of the signer. The top perspective is a top-down view of the signer. Usually, a sign will be written from a single perspective.