a combination of lights or positions on a railroad signal which has a defined meaning. This meaning is the signal's indication. AutoReversing: a feature of some DCC boosters which allows a train to enter and exit reversing sections automatically without the need for the operator to throw a switch to match track polarities on either side of the reversing section.

Each projection surface (family) can be positioned over the globe from one of four aspects (also referred to as perspectives or viewpoints): Polar - over the North or South Pole, Equatorial - over the equator, Transverse - 90 degrees from the normal position, or Oblique - over any mid-latitude location. The appearance of the graticule will vary depending on the projection aspect. Aspect should be selected so that the area of greatest interest takes central focus on the projected map.

Conceptual placement of a projection system in relation to the Earth's axis (direct, normal, polar, equatorial, oblique, and so on)

The orientation or position of a map projection graticule in respect to the lines of latitude and longitude on the globe they are representing. For example, the planar family of projections may be grouped into three aspects: polar, equatorial and oblique. (The term case", is also used in cartographic literature).

Individual azimuthal map projections are divided into three aspects: the polar aspect which is tangent at the pole, the equatorial aspect which is tangent at the Equator, and the oblique aspect which is tangent anywhere else. (The word "aspect" has replaced the word "case" in the modern cartographic literature.)