Combine two tables by rows using key variables, retaining unmatched rows.
Computes the relational outer join of tables A and B. This is like a regular join, but also includes rows in each input which did not have matching rows in the other input; the columns from the missing side are filled in with placeholder values.
TODO: Document options.
Returns: out - A table that is the result of the outer join of A and B ixa - indexes into A for each row in out ixb - indexes into B for each row in out