Question: How many values of r z (arcsecond) correspond with a r y (arcsecond) value of −0.247?
SQL: SELECT "r z ( Arcsecond )" FROM "1-15318324-1" WHERE "r y ( Arcsecond )" = '−0.247';

Question: How many values of r z(arcsecond) are associated with a target datum of Ireland 1965?
SQL: SELECT "r z ( Arcsecond )" FROM "1-15318324-1" WHERE "Target datum" = 'Ireland 1965';