Molecular biologists number RNA transcripts +1, +2, +3 and then to go in the other direction ... -1, -2, -3. They neglect the zero:
-3, -2, -1, +1, +2, +3It has become pervasive! Whenever they can avoid a zero they do. Some physicists I've spoken to about this were quite shocked.
This causes trouble if one wants to identify the location of a binding site with a sequence walker, and therefore is a bad practice. For details see the definition of a coordinate system.
This is a serious pitfall in molecular information theory, see Ignoring the number Zero.
origin: 1998 Jan 02
updated: 2011 Apr 07