When the match is complete a new table will be created which contains rows composed from the rows of the input tables - each row will contain entries corresponding to a single match. The Output Rows selector box allows you to choose on what basis rows will be included in this output table. In all cases each row will refer to only one matched "object" (any columns in the output come from only rows in the input tables which match according to the specified criteria), but you may or may not wish to see output rows which don't have a contribution from each of the input tables. For each input table therefore, you can choose to see the Matched Rows Only or All Rows. If you have All Rows, then the columns for which a match can't be found in one of the tables are just left blank.
By way of example: if your input tables are these:
X Y Vmag
- - ----
1134.822 599.247 13.8
659.68 1046.874 17.2
909.613 543.293 9.3
and
X Y Bmag
- - ----
909.523 543.800 10.1
1832.114 409.567 12.3
1135.201 600.100 14.6
702.622 1004.972 19.0
then a Cartesian match of the two sets of X and Y values with an error of 1.0
requiring Matched Rows Only for both tables would give you a
result like this:
X_1 Y_1 Vmag X_2 Y_2 Bmag MatchScore
--- --- ---- --- --- ---- ----------
1134.822 599.247 13.8 1135.201 600.100 14.6 0.933
909.613 543.293 9.3 909.523 543.800 10.1 0.515
while choosing All Rows for the first table would give you this:
X_1 Y_1 Vmag X_2 Y_2 Bmag MatchScore
--- --- ---- --- --- ---- ----------
1134.822 599.247 13.8 1135.201 600.100 14.6 0.933
659.68 1046.874 17.2
909.613 543.293 9.3 909.523 543.800 10.1 0.515
A couple of other points are illustrated in this example: since the join would have resulted in duplicate column names, the X and Y columns are renamed by appending a suffix. The MatchScore column which gets added is here simply the distance in Cartesian space between the points (X_1,Y_1) and (X_2,Y_2).