To link ontology terms with phenotypic systematic characters and taxa, we developed the Phenex curation tool [20].
Systematic characters are sometimes framed such that different character states involve different logical qualities (e.g., absent and shape).
This variability is described in systematic characters, which consist of two or more character states contrasting some aspect (e.g., morphology, behavior) of the taxa under study [14].
In applying the EQ formalism to systematic characters, it is helpful to distinguish several categories of characters that are commonly found in the systematics literature [17].
In systematic characters, entities and qualities can be found in the character description, in the character state description, or in both.
Many systematic characters, however, do not follow this format (see [14] for review), and a standardized logical framework, consistent with EQ formalism, has been recently proposed [14].
In comparing EQ syntax to systematic characters, the quality term represents the character state and, by implication through the subtype relationships of the quality ontology, the attribute of the character (e.g., sigmoid is a subtype of shape, Figure 1).
Thus, the utility of felid skull shape characters in systematic analyses [26] is questionable, owing to shape being highly size-dependent and not readily quantifiable into discrete systematic characters.
As previously described (Figure 1), systematic characters typically consist of a short character header (e.g., maxilla shape) denoting the relevant structure(s) (entity: maxilla) and attribute (high-level quality: shape) that varies among taxa, followed by several character states that specify the value of the quality (round, rectangular, triangular, etc).
The systematic character of Hansen's methods carried celestial mechanics to a new level of power and precision.
"As a black person, straying from the tenets of this orthodoxy meant that you were a traitor to your race, you were not a real black, and you would be forced to pay for your ideological trespasses, often through systematic character assassination, the modern-day version of the old public floggings.
