This is from KnitWitts,
"The most commonly misunderstood weight of yarn is DK. Not, double strands of yarn but a weight of yarn that falls in between sport and worsted. This weight comes to us from Europe and has a classic gauge of 5.5 sts=1" on US 6. Many yarns imported from Europe have this gauge and are now available on the American market. A true sport weight uses needle sizes between US 3 and 5 with an average gauge of 6 sts=1". Sport weight yarns are used for lighter weight garments including fair Isle work, babies and children’s garments and heavier socks"
http://www.knitwitts.com/category/Yarn/c22
And Sue posted this link
http://yarnforward.com/tension.html to help me understand (confuse me further)how to figure out yarns.
crocee AKA Andi