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When done, hitting "Create" and clicking on "Open resource here" will pull up the field set for the chosen section and allow you to enter the data for the given entry.
Resource Sections
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These can be anything from "customers" to "firewalls" to "cross-connects". Since you can customize the fields for these elements, you have flexibility in organizing the data.
Check out Customizing Sections and Customizing Fields for more details on how to fit these elements to your business.
Resource Categories
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Categories can be used to create some filtered views for given resources and sections.
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