A compositional series is defined by end-member stoichiometric phases and a non-stoichiometric range of compositions given between the end-member compositions. Consider, for example, the two solids Al2O3 and Cr2O3 as end members. The compositional series in which 5 to 15% of the Al atoms are replaced by Cr atoms, typically given in a format like

(Al1-xCrx)2O3: 0.05 ≤ x ≤ 0.15,

is encoded as
The SSAM-based annotation with marker sd employs the dictionary key emr to specify the second end member and the compositional range. This key expects the SFN-based CurlySMILES notation of the second end member. Range specification is done by continuing with a comma followed by the pair of exchanged atoms, followed by a colon, followed by the values for the range boundaries. Within each pair, the data are separated by a dash. The first atom of the pair is the one in the annotated notation that is replaced by the second atom of the pair to get the notation of the second end member.

Multiple substitutions are possible. The series representation

(Mg1-xFex)2(SiO4)1-y(GeO4)y: 0.1 ≤ x ≤ 0.6 and 0 ≤ y ≤ 0.3

can be translated into the following CurlySMILES notation:
{*Mg2(SiO4)}{sdemr={*Fe2(GeO4)},Mg-Fe:0.1-0.6, \
Notice that range specification is optional. A notation without range specification presents the whole range of a binary sytem in terms of its end phases. Compositional series, encoded in the format shown herein, may correspond to binary systems including solid solutions, alloys and salt mixtures. However, no particular atomic arrangement or structure is implied by the CurlySMILES notations using the emr format, unless additional annotation parameters do so.
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[1] A. Drefahl: CurlySMILES: a chemical language to customize and annotate encodings of molecular and nanodevice structures. J. Cheminf. 2011, 3:1; doi: 10.1186/1758-2946-3-1 .

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