The holes in this drawing have what kind of tolerance?

Bilateral tolerance means that the allowable deviation is specified in both directions from the nominal dimension.

In the provided drawing, the hole dimension is given with an equal tolerance range on both sides, indicating bilateral tolerance.

References: "Engineering Drawing and Design" by David A. Madsen and "Geometric Dimensioning and Tolerancing" by Alex Krulikowski discuss bilateral tolerances and theirrepresentation in technical drawings.