Letters and Other Symbols

The model for describing letterforms is discussed in some detail in the 'Describing Handwriting' series of blog posts on the DigiPal website. The discussion here is a condensed version of that which also includes some adjustments to the model as implemented in the DigiPal framework. The discussion here also draws heavily on the DigiPal Glossary and reproduces it in part.

The DigiPal model was conceived for describing handwriting and was originally applied to the Latin script. Since then it has been transferred to numerous other writing systems including Greek, Hebrew, Arabic and Chinese, and also to decoration. Indeed, it seems to be applicable to any system of graphic communication comprising common units that are produced by different individuals and which share a common meaning, be those letters, ideographs, hieroglyphs, or visual elements such as knots, birds, portraits of the Virgin, and so on. 'Symbol' is therefore used below to refer to any of these repeated elements which in many cases will be letters but may be other forms instead.

The Hierarchy of Symbols

Although used widely, the terms 'letter' and even 'letter-form' are very ambiguous in practice. They might refer to the shape of a letter in general, to the shape of a letter as typically written by an individual, a given mark on a given page, and so on. For this reason, the DigiPal framework includes a hierarchy of different 'letters', ranging from a given concrete instance on the page through to the abstract semantic notion, and similarly from the single instance produced by a single individual through to the abstract notion shared by a large group. The entities are defined below, in order moving up the hierarchy in a many-to-one relationship: every Graph must have one Idiograph, every Idiograph must have one Allograph, and so on, but an Idiograph can have many Graphs, an Allograph can have many Idiographs, and so on.

Graph: A single instance of a given sign written on the page.

Idiograph: The way (or one of the ways) in which an individual writes a given allograph.

Allograph: A recognised variant form of the same character (e.g. a and a, or Caroline and Insular d). Note that 'recognised' here is a somewhat arbitrary definition which will be determined by the particular needs of your research.

Character: Similar to sign; more or less a set of letters in the abstract sense but also including punctuation and abbreviations. So a, b, c etc. are characters, but so also is the full stop, question mark, accent mark ( ́), etc. However, 'character' does include some sense of physical form: in particular, it is used to distinguish between capital and minuscule/lower-case letters. Therefore a and A are different Characters but the same Ontograph.

Ontograph: A project-specific neologism, this represents the most abstract form of the letter without physical form. It is often equivalent to grapheme but may also be used for other signs such as punctuation, accents, and so on; it may therefore be considered as a generalised grapheme.

Describing Symbols

Components: Each of the entities listed above from Character down can have one or more Components. Their definition is again dependent on the writing system but may include 'ascender' (for b, d, h, l, k etc.), a radical in a Chinese character, and so on. The components should normally comprise 'essential elements' (following the terminology of Parkes, Their Hands Before Our Eyes), namely 'those characteristics of a letter shape, which enable a reader to distinguish one letter from another'. Each Component may correspond to a stroke in the letter but this is not necessary. Each symbol (Graph, Allograph etc.) must comprise one or more Components, and each Component may appear in one or more symbols.

Features: Features are attributes (essentially tags) which may be applied to Components. They normally represent the features of style in Parkes's terms (elements which 'embellish components of letter shapes, in order to enhance the image of a scribe's handwriting on the page'). They might therefore include serifs, decorative flourishes, elements of curvature, and so on. Each Feature may be associated with one or more Components, and each Component will normally have more than one Feature.

In principle, Features may be assigned to Components at any level of symbol. Thus the Allograph 'Insular h' may have the Component-Feature pair 'Ascender - Wedged', meaning that Insular h would normally have wedges on the ascender.