Take a look at this great blog from Gladys Koskas: Everything you need to know about QRadar Rules (for beginners and experts)
"This document is more like an advanced documentation, and you'll learn everything from "what are the different types of rules" to "how does the correlation engine processes the rules". There is a lot of information, but there is a table of contents so you can easily navigate to the parts that you are interested in."
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Wendy Batten
Community Manager
IBM Security
Cambridge MA
wjbatten@us.ibm.com------------------------------