Notational Systems – the Cognitive Dimensions of Notations framework

ion: types and availability of abstraction mechanisms. Abstractions (redefinitions) change the underlying notation. Macros, data structures, global findand-replace commands, quick-dial telephone codes, and word-processor styles are all abstractions. Some are persistent, some are transient. Abstractions, if the user is allowed to modify them, always require an abstraction manager -a redefinition sub-device. It will sometimes have its own notation and environment (e.g. the Word style sheet manager) but not always (for example, a class hierarchy can be built in a conventional text editor). Systems that allow many abstractions are potentially difficult to learn. Secondary notation: extra information in means other than formal syntax. Users often need to record things that have not been anticipated by the notation designer. Rather than anticipating every possible user requirement, many systems support secondary notations that can be used however the user likes. One example is comments in a programming language, another is the use of colours or format choices to indicate information additional to the content of text. Closeness of mapping: closeness of representation to domain. How closely related is the notation to the result it is describing?