Understand 'Change Action' meaning

Summary:

Content (required):

Under Item’s pending revision and a multi-row EFF attribute, the user can set view for column ‘Change Action’. Once he set it, the value we see is “Production”, while same column in redline (under the change) has the value ‘Update’. Can anyone explain the meaning of ‘Change action is Production’?

First screenshot is taken from an item, while 2nd is for the same item but through a change redline.

Version (include the version you are using, if applicable):

21c

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