biological character (noun, pl. biological characters) – a distinguishing feature that is characteristic for a particular, individual organism and can be used to differentiate, classify, or identify it as a member of a particular taxon. Each character is essentially a summary of the character states for attributes that describe biological structures. It can be observed or measured; e. g., a mycelium is a biological structure that has several structural attributes, one of those attributes is the mycelium colour, the most common character state for this attribute is "white". Biological characters are only informative, if they can be used to distinguish different organisms or taxa. Thus, biological information systems generally record information as character states that describe structural attributes of biological character. For example, the presence of a specific secondary metabolite may not be a physical structure like a cell or organ. Nevertheless, this chemistry represents information that can be interpreted as a element of a biologically informative character. The secondary metabolite atranorin may thus be recorded as the name of the secondary metabolite that has been reported from a particular lichen. In other words, atranorin represents one possible character state for the attribute that describes secondary metabolites as a biological character.