What is the minimum length for each arm of the cross when defining a corner?

• A. 3 cm
• B. 5 cm
• C. 7 cm
• D. 10 cm

Answer: (B)

In cartography, marking a corner with a cross is about clarity and precision. The arms of the cross must be long enough to be clearly visible and distinguishable from nearby lines and labels, even after printing or when the map is viewed at reduced scales. If the arms are too short, the symbol can become indistinct or disappear during reproduction, making the corner hard to locate exactly. On the other hand, making them much longer would overwhelm surrounding features and risk crowding the map.

Five centimeters is the practical minimum that maintains legibility while keeping the symbol compact. It provides enough prominence to be unmistakable without risking overlap with adjacent map elements. Shorter lengths like 3 cm are prone to faintness or loss of definition, whereas longer lengths such as 7 cm or 10 cm, while readable, can clutter the map. So five centimeters is the best balance for defining a corner.