[ Table of contents ]

3        Terms, definitions, symbols, and abbreviated terms

3.1        Terms and definitions

For the purposes of this document, the following terms and definitions apply. Symbols or abbreviations used as representations for the term are listed immediately following the term. After the definition, where necessary, an additional clarifying note may be provided. Terms defined in the body of this document are presented in italics at the point where they are defined. The Index provides a directory of those terms defined in the body of this International Standard.

3.1.1

Earth gravitational model

spherical harmonic expansion of the gravitational field potential

NOTE  Rotational effects are not included in this model; gravity includes rotational effects.

3.1.2

ecliptic plane

plane defined by the orbit of a planet at a point in time

3.1.3

equatorial plane

plane through a designated centre of an object and normal to the rotational axis of the object

3.1.4

geodetic datum

datum describing the relationship of a coordinate system to the Earth [ISO 19111]

NOTE          In most cases, the geodetic datum includes an ellipsoid definition.

3.1.5

north pole

that pole of rotation that lies on the north side of the invariable plane of the solar system [RIIC]

NOTE 1       Some planets have retrograde rotation with respect to this definition.

NOTE 2       Map north (see Clause 5) may be unrelated to this direction.

3.1.6

spatial object

physical or virtual object to which spatial information applies

3.1.7

spatial operation

mathematical function that re-expresses coordinates, directions, and/or distances expressed in one spatial reference frame in terms of a different spatial reference frame or a mathematical function for distance or other geometric quantities within a single spatial reference frame

3.2        Notation, symbols and abbreviated terms

Table 3.1 lists the mathematical notation conventions used in this document.

Table 3.1 — Mathematical notation

 

Upper case italic letter symbols are also used for scalar-valued functions that are customarily capitalized.

EXAMPLE     R_N in Table 5.6.

Table 3.2 lists the symbols used in this document.

Table 3.2 — Symbols

 

Table 3.3 lists the abbreviated terms used in this document. In the specification of an abbreviation, the letters in the abbreviated term used to form the abbreviation are presented in upper-case and other letters are presented in lower-case with one exception. When the abbreviated term includes another abbreviation that is used to form the abbreviation for that term, all the letters of the included abbreviation are presented in upper-case even if all of the letters are not used in the formed abbreviation.

Table 3.3 — Abbreviated terms