Okay, I need to classify this bug report about QEMU into either 'user-mode' or 'system-mode'. The issue is about indentation using spaces instead of tabs in the net subsystem. Hmm, so the net subsystem probably relates to network drivers or how networking is handled in QEMU. Since QEMU involves virtualization and interacts with hardware and lower-level system components, this sounds like it's part of the system-mode code. Indentation issues might affect readability but could also impact functionality if not consistent, especially in kernel modules or device drivers which are typically system-mode. Therefore, I think this is a system-mode related bug report. system