This IBM Support web page describes many of the IBM i system jobs,
This IBM Support web page provides an introductory overview of the Work Control Block Table (WCBT).
This IBM Support web page provides basic information about IBM i LIC logs (also known as VLOGs).
Thie IBM Support page lists the technology refresh levels and related technology refresh group PTF level for the latest IBM i releases.
This IBM Support page is the main page from which you can go to specific PSP documents for various IBM i releases.