What type of requirements are printed in italic type in Handbook 44?

The correct answer is nonretroactive requirements, which are printed in italic type in Handbook 44. This format is used to indicate that these requirements do not apply retroactively to equipment or systems that are already in use at the time the requirement becomes effective.

By emphasizing nonretroactive requirements in italics, Handbook 44 clearly communicates that while new guidelines or standards are being introduced, they will not affect devices that were installed or tested before the implementation date. This provides clarity and helps manage compliance expectations for manufacturers, regulators, and end-users.

In contrast, mandatory requirements are typically presented in a standard format, signifying that they must be followed without exceptions. Performance-based requirements focus on the outcomes rather than the method, which would not necessitate italics for differentiation. Voluntary requirements are those that can be adopted at the discretion of the user and are not enforced; thus, they also would not require special formatting.