Mjoin - Retreiving additional columns from joined table

I have the following server and client scripts and need to retrieve additional columns from the joined table program_outcome. In this instance, the additional column is program_outcome.type.. How should I do this?

Server side:

Editor::inst( $db_cm_dopt, 'unit_outcome', 'unit_outcome_pk' )    
    ->field(
        Field::inst( 'unit_outcome.unit_outcome' ),
        Field::inst( 'unit_outcome.modified' ),
        Field::inst( 'unit_outcome.modified_by' )->setValue( $user )
    )
     ->join(
        Mjoin::inst( 'unit' )
            ->link( 'unit_outcome.unit_outcome_pk', 'unit_unit_outcome_lookup.unit_outcome_fk' )
            ->link( 'unit.unit_pk', 'unit_unit_outcome_lookup.unit_fk' )
            ->order( 'unit.unit_full_name asc' )
            ->fields(
                Field::inst( 'unit_pk' )
                    ->options( Options::inst()
                        ->table( 'unit' )
                        ->value( 'unit_pk' )
                        ->label( 'unit_full_name' )               
                    ),
                Field::inst( 'unit_full_name' )
            )
    )
     ->join(
        Mjoin::inst( 'program_outcome' )
            ->link( 'unit_outcome.unit_outcome_pk', 'program_outcome_unit_outcome_lookup.unit_outcome_fk' )
            ->link( 'program_outcome.program_outcome_pk', 'program_outcome_unit_outcome_lookup.program_outcome_fk' )
            ->order( 'program_outcome.program_outcome asc' )
            ->fields(
                Field::inst( 'program_outcome_pk' )
                    ->options( Options::inst()
                        ->table( 'program_outcome' )
                        ->value( 'program_outcome_pk' )
                        ->label( 'program_outcome' )
                        ->render( function ( $row ) {
            return strip_tags($row['program_outcome']);
        } )
                        ->order( 'program_outcome' )
                    ),
                Field::inst( 'program_outcome' )
            )
    )
    ->process($_POST)
    ->json();