public void appendPlayerUpdateBlock(Stream str){
		if(str != null) {
			if(!updateRequired && !isChatTextUpdateRequired())
				return;		// nothing required
		synchronized(this) {
			//TODO: Cache Update Block
			int updateMask = 0;
			if(mask100update) {
				updateMask |= 0x100;
			}
			if(animationRequest != -1) {
				updateMask |= 8;
			}
			if(forcedChatUpdateRequired) {
				updateMask |= 4;
			}
			if(isChatTextUpdateRequired()) {
				updateMask |= 0x80;
			}
			if(isAppearanceUpdateRequired()) {
				updateMask |= 0x10;
			}
			if(faceUpdateRequired) {
				updateMask |= 1;
			}
			if(FocusPointX != -1) {
				updateMask |= 2;
			}
			if (isHitUpdateRequired()) {
				updateMask |= 0x20;
			}

			if(hitUpdateRequired2) {
				updateMask |= 0x200;
			}

			if(updateMask >= 0x100) {
				updateMask |= 0x40;
				str.writeByte(updateMask & 0xFF);
				str.writeByte(updateMask >> 8);
			} else {
				str.writeByte(updateMask);
			}

			// now writing the various update blocks itself - note that their order crucial
			if(mask100update) {
				appendMask100Update(str);
			}
			if(animationRequest != -1) {
				appendAnimationRequest(str);
			}
			if(forcedChatUpdateRequired) {
				appendForcedChat(str);
			}
			if(isChatTextUpdateRequired()) {
				appendPlayerChatText(str);
			}
			if(faceUpdateRequired) {
				appendFaceUpdate(str);
			}
			if(isAppearanceUpdateRequired()) {
				appendPlayerAppearance(str);
			}
			if(FocusPointX != -1) {
				appendSetFocusDestination(str);
			}
			if(isHitUpdateRequired()) {
				appendHitUpdate(str);
			}
			if(hitUpdateRequired2) {
				appendHitUpdate2(str);
			}
		  }
	   }
	}