First off big kudos to @Venni Mäkäräinen for his spot on CSDM & Request Catalogue - service offering and catalog item association article. This article expands on his work and provides the different service offering types and a model to identify them. All of this ties into the CSDM model and Service Offerings that are manifested as requestable Catalog Items in the Service Catalog. But how do you approach and identify all the Service Offerings and Service types?

ServiceNow has what is called Service Modeling...

What is Service Modelling?

A common way to arrange services, categorizing technologies into service offerings that help model the specific impacts the organization needs to manage, there driving greater service visibility.

The specific areas to look at to identify the different variables for service offerings, to allow enterprise manage consumption / reporting in underlying technology:

• Business Processes
• Process stage (i.e., customer journey, process phase, chevron, or activity)
• Product Lines
• Brands
• Ways of accessing a service or different service channels
• Ownership
• Service Commitments
• Technology architecture / Technology types / brands, features & or platforms
• Environment

Service Definition Process - High level

Service Modeling Decision Tree Guidance