An early method of producing well-organized, paragraph-length descriptions and comparisons was pioneered in the TEXT system of McKeown (1985), which used ATN-like organizational schemas to sequence sections of the description of a type of object, such as the object's more general type, its major parts and distinctive attributes, and illustrative examples. Later work by Hovy (1988) and Moore and Paris (1988) tied content planning more closely to communicative goals by relying on rhetorical structure theory (RST) (Mann and Thompson 1987). RST posits over 20 possible coherence relations between spans of text (usually adjacent).  For example, a statement of some claim may be followed by putative evidence for the claim, thus establishing an evidence relation between the claim (called the nucleus, because it is the main point) and the cited evidence (called a satellite because of its subsidiary role).  Another example is the volitional result relation, where the nuclear text span describes a situation or event of interest, and the satellite describes a deliberate action that caused the situation or event. Often these relations are signalled by discourse markers (cue words and phrases), such as but, when, yet, or after all, and it is important in text generation to use these markers appropriately. For example, the use of when in the following sentence enhances coherence,