What do heavy gray corners around drawing views indicate?

Heavy gray corners around drawing views indicate that the component has been changed outside the assembly. When a component is modified externally—such as through a different file, by another user, or through updates not captured within the current assembly context—the visual cue of heavy gray corners alerts users to discrepancies that need to be addressed. This helps ensure accuracy and consistency across the design, prompting users to either update the drawing view to reflect the changes or investigate further to reconcile differences between the drawing and the actual assembly.

Knowing this condition is crucial for maintaining integrity in design processes, particularly in collaborative environments where multiple team members may alter files, thereby affecting reference drawings and views. Being aware of such visual indicators assists in producing reliable documentation when preparing for presentations, manufacturing, or further design iterations.