a unit of textual information such that a sequence of characters defines an abstract text that can be written or recited in various concrete ways all of which are obviously presenting the same underlying text

An atomic unit of textual communication; for example, the letter .

a unit of information used for the organization, control or representation of textual data. Abstract characters may be non-graphic characters used in textual information systems to control the organization of textual data (e.g. U+FFF9 INTERLINEAR ANNOTATION ANCHOR), or to control the presentation of textual data (e.g. U+200D ZERO WIDTH JOINER).