Final answer:
ITIL complementary guidance provides resources such as case studies and white papers to assist organizations in integrating ITIL practices into their specific context. These are not mandatory regulations but are meant to enhance understanding and application of ITIL best practices.
Step-by-step explanation:
ITIL complementary guidance refers to additional published guidance that aims to assist organizations with the adaptation and integration of ITIL best practices into their specific environments. This guidance offers a range of resources, including case studies, white papers, and publications that focus on industry-specific contexts, such as public sector or financial services, and provide advice for applying ITIL practices in various cultural environments, different organizational sizes or different types of service providers. These resources are not mandatory, but they are intended to supplement the main ITIL framework by providing insights and recommendations that may be particularly relevant to certain areas of business or service management.