Final answer:
A cylindrical tolerance zone is typically represented by two parallel lines or the Greek letter phi (Φ) in technical drawings, as part of geometric dimensioning and tolerancing practices.
Step-by-step explanation:
The symbol used to specify a cylindrical tolerance zone in engineering and technical drawings is generally two parallel lines (or sometimes the Greek letter phi, Φ). In geometric dimensioning and tolerancing (GD&T), these symbols are used in conjunction with specific annotations to define the size, position, and form tolerances where a cylindrical geometry is required. However, without the specific context of the diagram or the associated standards (such as ASME Y14.5 or ISO 1101), it is difficult to provide a precise symbol. Cylindrical tolerance zones are crucial in making sure that mating parts fit together properly, and the applied tolerances ensure that the parts are manufactured within acceptable variations while maintaining the intended function.