<xsd:element name="space_group" minOccurs="0" maxOccurs="unbounded">
<xsd:complexType>
<xsd:all>
<xsd:element name="IT_number" minOccurs="0" maxOccurs="1" nillable="true">
<xsd:annotation>
<xsd:documentation xml:lang="en">The number as assigned in International Tables for Crystallography Vol. A, specifying the proper affine class (i.e. the orientation-preserving affine class) of space groups (crystallographic space-group type) to which the space group belongs. This number defines the space-group type but not the coordinate system in which it is expressed.</xsd:documentation>
</xsd:annotation>
<xsd:simpleType>
<xsd:restriction base="xsd:integer">
<xsd:minInclusive value="1"/>
<xsd:maxInclusive value="230"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<xsd:element name="crystal_system" minOccurs="0" maxOccurs="1" nillable="true">
<xsd:annotation>
<xsd:documentation xml:lang="en">The name of the system of geometric crystal classes of space groups (crystal system) to which the space group belongs. Note that rhombohedral space groups belong to the trigonal system.</xsd:documentation>
</xsd:annotation>
<xsd:simpleType>
<xsd:restriction base="xsd:string">
<xsd:enumeration value="triclinic"/>
<xsd:enumeration value="monoclinic"/>
<xsd:enumeration value="orthorhombic"/>
<xsd:enumeration value="tetragonal"/>
<xsd:enumeration value="trigonal"/>
<xsd:enumeration value="hexagonal"/>
<xsd:enumeration value="cubic"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<xsd:element name="name_H-M_alt" minOccurs="0" maxOccurs="1" nillable="true" type="xsd:string">
<xsd:annotation>
<xsd:documentation xml:lang="en">attribute name_H-M_alt in category space_group allows any Hermann-Mauguin symbol to be given. The way in which this item is used is determined by the user and in general is not intended to be interpreted by computer. It may, for example, be used to give one of the extended Hermann-Mauguin symbols given in Table 4.3.2.1 of International Tables for Crystallography Vol. A (2002) or a Hermann-Mauguin symbol for a conventional or unconventional setting. Each component of the space-group name is separated by a space or an underscore. The use of a space is strongly recommended. The underscore is only retained because it was used in old CIFs. It should not be used in new CIFs. Subscripts should appear without special symbols. Bars should be given as negative signs before the numbers to which they apply. The commonly used Hermann-Mauguin symbol determines the space- group type uniquely but a given space-group type may be described by more than one Hermann-Mauguin symbol. The space- group type is best described using attribute IT_number. in category space_group The Hermann-Mauguin symbol may contain information on the choice of basis, but not on the choice of origin. To define the setting uniquely, use attribute name_Hall in category space_group or list the symmetry operations. three examples for space group No. 63 loop_ _space_group.name_H-M_alt 'C m c m' 'C 2/c 2/m 21/m' 'A m a m'</xsd:documentation>
</xsd:annotation>
</xsd:element>
<xsd:element name="name_Hall" minOccurs="0" maxOccurs="1" nillable="true" type="xsd:string">
<xsd:annotation>
<xsd:documentation xml:lang="en">Space-group symbol defined by Hall. Each component of the space-group name is separated by a space or an underscore. The use of a space is strongly recommended. The underscore is only retained because it was used in old CIFs. It should not be used in new CIFs. attribute name_Hall in category space_group uniquely defines the space group and its reference to a particular coordinate system. Ref: Hall, S. R. (1981). Acta Cryst. A37, 517-525; erratum (1981), A37, 921. [See also International Tables for Crystallography Vol. B (2001), Chapter 1.4, Appendix 1.4.2.] equivalent to Pca21 P 2c -2ac equivalent to Ia3d -I 4bd 2ab 3</xsd:documentation>
</xsd:annotation>
</xsd:element>
</xsd:all>
<xsd:attribute name="id" use="required" type="xsd:string">
<xsd:annotation>
<xsd:documentation xml:lang="en">This is the unique identifier for the SPACE_GROUP category.</xsd:documentation>
</xsd:annotation>
</xsd:attribute>
</xsd:complexType>
</xsd:element> |