Nothing marks the change in clothes from last season to next more dramatically than the belted waistline. Whether the clothes have fullness or are paired down to sleeky slim, they are often belted, tied or sashed.

The newest crop of waistline markings are the cummerbunds in endless variety, often wrapped obi-style and tied at the front.

The belted waistline is not only a mark of new clothes, but an unbeatable way to update favorite clothes in your closet. Jackets and coats are likely to take on a fresh look with the addition of a narrow belt. Those big dresses, sweaters and shirts often look totally different when belted and often can be worn with lots of different belts.

No need to try to match the belt to the constume. Contrasts, even as unexpected as a silver-tipped cowboy belt on a tweed jacket, add an amusing look. And some of the new cummerbunds and belts in bright, clear colors add a pleasing flash of brilliance to an understated costume. CAPTION: Pictures 1, 2, 3, 4, 5, and 6, From left:

Geoffrey Beene's crepe de chine suit with cummerbund; Paula Saker's double-belted flax linen blazer over a button-front linen skirt; silk linen skirt with attached cummerbund, paired with a silk shirt by Pinky and Dianne for Private Label; Calvin Klein's linen kimono wrapped with a natural cotton belt; Halston's black wrap dress sashed with black satin, and Gil Aimbez's pepum-effect, tightly-belted jacket with a deep slit skirt. Far left photo by Donal F. Holway; above and far right photos by Margaret Thomas