International
Tables for Crystallography Volume A Spacegroup symmetry Edited by Th. Hahn © International Union of Crystallography 2006 
International Tables for Crystallography (2006). Vol. A, ch. 1.3, pp. 56
doi: 10.1107/97809553602060000502 Chapter 1.3. Printed symbols for symmetry elements^{a}Institut für Kristallographie, RheinischWestfälische Technische Hochschule, Aachen, Germany This chapter lists the printed symbols for symmetry elements and symmetry operations used throughout this volume. The list is accompanied by notes and crossreferences to recent IUCr nomenclature reports. 
1.3.1. Printed symbols for symmetry elements and for the corresponding symmetry operations in one, two and three dimensions
For `reflection conditions', see Tables 2.2.13.2 and 2.2.13.3 .
^{†}In the rhombohedral spacegroup symbols (161) and (167), the symbol c refers to the description with `hexagonal axes'; i.e. the glide vector is , along [001]. In the description with `rhombohedral axes', this glide vector is , along [111], i.e. the symbol of the glide plane would be n: cf. Section 4.3.5
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^{‡}For further explanations of the `double' glide plane e, see Note (x) below. ^{§}Glide planes d occur only in orthorhombic F space groups, in tetragonal I space groups, and in cubic I and F space groups. They always occur in pairs with alternating glide vectors, for instance and . The second power of a glide reflection d is a centring vector. ^{¶}Only the symbol m is used in the Hermann–Mauguin symbols, for both point groups and space groups. ^{††}The inversion point is a centre of symmetry if n is odd. 
For the e glide planes, new graphical symbols were introduced (cf. Sections 1.4.1 , 1.4.2 , 1.4.3 and Note iv in 1.4.4 ); they are applied to the diagrams of the relevant space groups: Seven orthorhombic A, C and Fspace groups, five tetragonal Ispace groups, and five cubic F and Ispace groups. The e glide plane occurs only in centred cells and is defined by one plane with two perpendicular glide vectors related by a centring translation; thus, in Cmma (67), two glide operations a and b through the plane xy0 occur, their glide vectors being related by the centring vector ; the symbol e removes the ambiguity between the symbols a and b.
For five space groups, the Hermann–Mauguin symbol has been modified:

The new symbol is now the standard one; it is indicated in the headline of these space groups, while the former symbol is given underneath.
For the k glide planes, no new graphical symbol and no modification of a spacegroup symbol are proposed.
References
Flack, H. D., Wondratschek, H., Hahn, Th. & Abrahams, S. C. (2000). Symmetry elements in space groups and point groups. Addenda to two IUCr Reports on the Nomenclature of Symmetry. Acta Cryst. A56, 96–98.Wolff, P. M. de, Billiet, Y., Donnay, J. D. H., Fischer, W., Galiulin, R. B., Glazer, A. M., Senechal, M., Shoemaker, D. P., Wondratschek, H., Hahn, Th., Wilson, A. J. C. & Abrahams, S. C. (1989). Definition of symmetry elements in space groups and point groups. Report of the International Union of Crystallography Adhoc Committee on the Nomenclature of Symmetry. Acta Cryst. A45, 494–499.
Wolff, P. M. de, Billiet, Y., Donnay, J. D. H., Fischer, W., Galiulin, R. B., Glazer, A. M., Hahn, Th., Senechal, M., Shoemaker, D. P., Wondratschek, H., Wilson, A. J. C. & Abrahams, S. C. (1992). Symbols for symmetry elements and symmetry operations. Final Report of the International Union of Crystallography Adhoc Committee on the Nomenclature of Symmetry. Acta Cryst. A48, 727–732.