private void writeNetscapeApplicationBlock(OutputStream os, int loopCounts) throws Exception {
    	byte[] buf = new byte[19];
 		buf[0] = EXTENSION_INTRODUCER; // Extension introducer
 		buf[1] = APPLICATION_EXTENSION_LABEL; // Application extension label
 		buf[2] = 0x0b; // Block size
 		buf[3] = 'N'; // Application Identifier (8 bytes)
 		buf[4] = 'E';
 		buf[5] = 'T';
 		buf[6] = 'S';
 		buf[7] = 'C';
 		buf[8] = 'A';
 		buf[9] = 'P';
 		buf[10]= 'E';
 		buf[11]= '2';// Application Authentication Code (3 bytes)
 		buf[12]= '.';
 		buf[13]= '0';
 		buf[14]= 0x03;
 		buf[15]= 0x01;
 		buf[16]= (byte)(loopCounts&0xff); // Loop counts
 		buf[17]= (byte)((loopCounts>>8)&0xff);
 		buf[18]= 0x00; // Block terminator 
 		
 		os.write(buf);
    }
Write out a zero length data sub-block
subs/gif-revert/src/main/java/com/engineer/gif/revert/lib/AnimatedGIFWriter.java