void startGroup(Chain chain, String group3, int groupSequenceNumber, char groupInsertionCode, int firstAtomIndex) {
		if (groupCount == group3s.length) {
			chains = (Chain[]) ArrayUtil.doubleLength(chains);
			group3s = ArrayUtil.doubleLength(group3s);
			seqcodes = ArrayUtil.doubleLength(seqcodes);
			firstAtomIndexes = ArrayUtil.doubleLength(firstAtomIndexes);
		}
		firstAtomIndexes[groupCount] = firstAtomIndex;
		chains[groupCount] = chain;
		group3s[groupCount] = group3;
		seqcodes[groupCount] = Group.getSeqcode(groupSequenceNumber, groupInsertionCode);
		++groupCount;
	}