Compositing CGI with Bigger Node Trees - Nuke 101: Professional Compositing and Visual Effects - page 123

You'll repeat this process three more times to connect the Indirect (Ind), Specular
(Spc),andShdSelf(SelfShadow)passes.Youwillcopythesamelineandbranch,
and then paste it back into the last bottom right Dot, connecting the Merge node
and changing the Shuffle node, and sometimes the Merge node's Operation prop-
erty.
28. Repeat the process. Select the last line starting from the bottom right Dot and
ending in the bottommost Merge node, copy, and then branch-paste to the bottom
right Dot. Connect the new Merge's B input to the previous Merge node.
29. This time, change the Shuffle node's In property to Ind. Don't change the Merge
node's Operation property.
30. Repeat the process, this time for the Spc pass.
31. Go through the process a third time. Choose ShdSelf for the Shuffle node's In
property, and change the Merge operation to Minus.