Question

a keynote is a number or letter that is used with a leader and arrowhead to identify a specific object; it usually appears in -----. block letters the upper left - hand corner a square or circle the upper right - hand corner

Explanation:

A keynote is a number or letter used with a leader and arrowhead to identify a specific object. In technical drawings and diagrams, it is standard practice to place the keynote in a square or circle. This visual convention helps in clearly associating the identifier with the object it refers to. Block letters are more about the style of writing text rather than the placement of a keynote. The upper left - hand corner or upper right - hand corner are not the typical standard placements for a keynote in relation to its function of object identification with a leader and arrowhead.

Answer:

a square or circle