Extendable essay as a hypertext scheme for information and educational material

A hypertext scheme for an extendable essay, i.e., a brief presentation of educational, scientific, informative, or reference material with supplementary, bibliographic, illustrative and other optional extensions is proposed. A particular example of an extendable essay is described. The differences between extendable essays and available hypertext schemes are discussed. An implementation of the scheme that makes it possible to create extendable essays of any content is described.