The file format of meta-atoms has four, separated by a space, elements in the following order:
R/C///C/R LinearGeneralEthyne L-CtC LinearStructureR/C///N LinearGeneralNitrile L-CN LinearStructureR/H LinearHydrogenAtom L-H LinearStructureR/'Br' LinearBromineAtom L-Br LinearStructureR/'Cl' LinearChlorineAtom L-Cl LinearStructureR/'I' LinearIodineAtom L-I LinearStructure