Explain the three outputs of the Join tool.

L holds rows from the left input that found no match, J holds rows that matched — the inner join — and R holds unmatched rows from the right input.

Having all three at once is genuinely useful compared with SQL, where an inner join silently discards the non-matches. Here they are on an anchor waiting to be inspected or written out as an exception report.

To reproduce SQL join types you union the anchors: J alone is inner, J with L is left, all three is full outer.