Your customer complains that when their users click on the Configuration Item magnifier from the...

To exclude certain types of CIs from the CI lists on the Incident, Problem, and Change forms, you can use the Principal CI class checkbox, which is available on the Class Manager module under Configuration1.

The Principal CI class checkbox allows you to specify which CI classes are considered as principal CIs, meaning they are the most relevant and important CIs for the business services and processes1. By default, only the CI classes that have this checkbox selected are displayed on the CI lists on the Incident, Problem, and Change forms2.

To use this feature, you need to navigate to the Class Manager module, select the CI class that you want to exclude or include, and check or uncheck the Principal CI class checkbox accordingly1. You can also use the Filter option to search for the CI classes by name or label1.

The other options are not recommended or valid ways to exclude certain types of CIs from the CI lists. Adding a Show field to the base cmdb table would require modifying the table schema and creating a reference qualifier, which could affect the performance and integrity of the CMDB3. Creating an Access control to hide the unnecessary CIs from the itil users would require defining the conditions and roles for the access rule, which could be complex and error-prone4. Making a show/hide UI action to show only the desired CIs to the itil users would require creating a custom script and UI element, which could be incompatible with the existing UI and functionality. References: 1: Principal configuration item classes 2: Configuration item lists 3: CMDB table schema 4: Access control rules : [UI actions]