private void  Initialize(SegmentInfo si)
		{
			segment = si.name;
			
			// Use compound file directory for some files, if it exists
			Directory cfsDir = Directory();
			if (Directory().FileExists(segment + ".cfs"))
			{
				cfsReader = new CompoundFileReader(Directory(), segment + ".cfs");
				cfsDir = cfsReader;
			}
			
			// No compound file exists - use the multi-file format
			fieldInfos = new FieldInfos(cfsDir, segment + ".fnm");
			fieldsReader = new FieldsReader(cfsDir, segment, fieldInfos);
			
			tis = new TermInfosReader(cfsDir, segment, fieldInfos);
			
			// NOTE: the bitvector is stored using the regular directory, not cfs
			if (HasDeletions(si))
				deletedDocs = new BitVector(Directory(), segment + ".del");
			
			// make sure that all index files have been read or are kept open
			// so that if an index update removes them we'll still have them
			freqStream = cfsDir.OpenFile(segment + ".frq");
			proxStream = cfsDir.OpenFile(segment + ".prx");
			OpenNorms(cfsDir);
			
			if (fieldInfos.HasVectors())
			{
				// open term vector files only as needed
				termVectorsReader = new TermVectorsReader(cfsDir, segment, fieldInfos);
			}
		}