My picture shows a prototyping board that I have. Sorry that the contrast is not great, but there are two vertical rows of connector like pads down the left and right sides of the board. They are oval. They look like they're for some sort of board connection, but there are no through holes.
If you solder wires to them, then what? If you solder a connector wire to the board, and another leading to a component, they'll just come apart when trying to solder each other one. I can't think of any suitable mechanical connector either.
What are they for, and are there any examples of their use?
Subsequently to this post, I've discovered that there are lots of these boards available at Chinese bulk buy sites (as my example below). They come in all sizes right up to 150mm across. I use them a lot for projects, but still haven't discovered an appropriate use for the edge pads. Others must also use them frequently, so...