If a schematic carries no legend, clues about it may be found in the parts list, drawing title, and?

The correct choice focuses on the significance of the engineer's notes as a valuable source of information when a schematic lacks a legend. These notes typically provide insights into the intended design, functionality, and specific instructions related to the schematic, which can be crucial for understanding its components and their interconnections. The engineer's notes might also clarify unusual symbols or practices that are not standardized, giving the reader context that is vital for accurate interpretation.

In contrast, while manufacturer's documentation, component descriptions, and previous schematics might offer helpful information, they don't necessarily provide the specific insights or clarifications associated with the current schematic being analyzed. Manufacturer documentation might outline general characteristics of components but won’t address how they specifically relate to the schematic at hand. Component descriptions could help identify parts, and previous schematics may provide a historical context, but engineer's notes directly connect to the specific schematic's intent and design nuances, making them particularly relevant when a legend is absent.