Streams is all about the rules; literally. The action context that a Streams process takes is governed by the rule conditions. When you create a rule, Oracle generates system conditions, and evaluation contexts, that are used to evaluate each LCR to determine if the action context for the process should be accomplished. We have already addressed a number of these system conditions during our TAG discussion; for instance
INCLUDE_TAGGED_LCR=FALSE generates a system evaluation for the
LCR$_ROW_RECORD_TYPE :dml.is_null_tag='Y' subprogram.
For more information on LCR Types, reference Oracle Database PL/SQL Packages and Types Reference manual.
You can control what system evaluations are included in the rule by the parameter ...