very old coding scheme this is where I'm back when you want to send let's say you just have a effectively a line the communication line over which all you could send was let's say voltage going on and back down you can make it go up briefly or go go up for longer for three times as long so a dot is a brief spike in or up in your voltage let's say and then a dash is three times as long and then the spaces in between the dot and dash are also encoding that it's it's quiet the reason it's a quiet time in between