How to assign persistentusbdevices

[PieterS]

To be sure that after remove usbplugs from my Pi and reconnect them without worrying which one connects where..
I try to implement the suggestions as described in the wiki. See https://www.domoticz.com/wiki/PersistentUSBDevices

But I do not fully understand these points:

• Is this the way to be sure that it does not matter in which USB-port I plug the different devices?

• When there is no file named 99-usb-serial.rules I create it there?

• Is this a good example for that file?

SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="123YAOOW", SYMLINK+="ttyUSB-RFX433"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0658", ATTRS{idProduct}=="0200", SYMLINK+="ttyUSB-ZStick-5G"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A7XKCMHJ", SYMLINK+="ttyUSB-P1"

Can someone confirm that the above code is correct? I want to create the code on a production-system..

Another last question:
The WIKI suggests that there will be only 2 new USB-ports...

After the reboot you should have two new serial ports (ttyUSB21 and ttyUSB22), and they will always be assigned to the devices you have configured in the rules file.

In the "rules-file" they declare 5 devices..
Can somebody explain that to me?