A directional representation (vector or field) for binary variables, i.e. with plus/minus, up/down, forward/back, right/left alternative states such as charge and spin. Macroscopic examples include the Earth’s poles (spin axis) and conventions in vehicular traffic flow. In molecules a displacement of the center of all negative charges from the positive center produces a dipole (or quadrapole, etc.). Linear sequences such as DNA carry information (genetic code) that is read in one direction (‘sense’) from one strand; the protein that is formed in this transcription/translation process is colinear with the code and formed in one directional sense (amino end to carboxyl end).
