### Prefix Area

The prefix area of the Source window is the leftmost column in the main area of the window. In a source view, the values in the prefix area correspond to the line numbers in the current source file. In a disassembly view, they correspond to the hexadecimal addresses of machine language instructions. In a mixed view, both line numbers and hex addresses are shown.

You can use the prefix area in the following ways:

- To get a bearing on where you are in your file, by using line numbers as references.
- To set and clear breakpoints. Double-click mouse button 1 on a value in the prefix area, or press the space bar while the cursor is in the prefix area. This toggles between setting and removing a breakpoint.
- To run or jump to a line. Click mouse button 2 [note] over the line's prefix area, and select either Run to location or Jump to location from the popup menu.

Breakpoints are indicated in the prefix area by reverse red highlighting.