byte[] getReverseModMapData() {
		
		// Allocate map based upon number of buffers corresponding to latest version changes
		int bitMapSize = (maxBufCount + 7) / 8;
		byte[] data = new byte[bitMapSize];
		Arrays.fill(data, (byte)0);
		
		// Mark excess bits corresponding to maxBufCount and beyond as changed
		int excess = maxBufCount % 8;
		if (excess != 0) {
			data[bitMapSize-1] |= (byte)(0xff << excess);
		}
		for (int index : bufferMap.getKeys()) {
			if (index >= maxBufCount) {
				System.err.println("VersionFileHandler: unexpected buffer index");
				continue;
			}
			setMapDataBit(data, index);
		}
		return data;
	}
Returns a bit map corresponding to all buffers modified since
the original version (e.g., oldest).  This identifies all buffers within the target
version (e.g., latest) which must be reverted to rebuild the original version.
NOTE: The bit mask may identify buffers which have been removed in the current version.
Ghidra/Framework/DB/src/main/java/db/buffers/VersionFileHandler.java