CREATE TABLE table_20297668_1 (yarn_type__us_ VARCHAR2, standard_yarn_weight_system VARCHAR2)

Name the yarn type for standard yarn weight system for 3 or light
SELECT yarn_type__us_ FROM table_20297668_1 WHERE standard_yarn_weight_system = "3 or Light"
SELECT "yarn_type__us_" FROM "table_20297668_1" WHERE "3 or Light" = "standard_yarn_weight_system"