Scanning in Medved Trader is tied to a Portfolio window. It allows you to add a scanning algorithm to a portfolio.
The scan would execute, for each row in the portfolio, a mathematical formula involving the symbol's parameters and technical indicators calculated for that symbol. This would happen continuously, as new data comes in.
The scan, for each row, would produce a Scan Result that can be displayed in the portfolio and can be used to sort the portfolio or show/hide some rows.
The Scan algorithm is very similar to a Paintbar algorithm and the editor for both is exactly the same. The only difference is that scans can produce Scan Results. In fact, you can use a Scan as a Paintbar and a Paintbar as a Scan.