Type custom fields are used only to customize the information in equipment types.
For understanding custom fields in general you should look at this section.
Equipment type custom fields
For creating and editing equipment type custom fields, you should head to the equipment module and choose SETTINGS > TYPE CUSTOM FIELDS as shown below.
Here you will see and manage type custom fields.
Create/Edit type custom fields
Creating and editing custom fields is done in the same way for all modules.
Assigning custom fields
When editing a piece of equipment you will see that the newly created fields are available to you.
You will also see the change in the custom fields when editing the equipment type.
Show custom field
When saving a piece of equipment, the newly added custom field will be available on the front of the page.