SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "AA" IN EACH CHAIN ON SHEET RECORDS BELOW ... SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "AA" IN EACH CHAIN ON SHEET RECORDS BELOW IS ACTUALLY AN 14-STRANDED BARREL THIS IS REPRESENTED BY A 15-STRANDED SHEET IN WHICH THE FIRST AND LAST STRANDS ARE IDENTICAL. SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "BA" IN EACH CHAIN ON SHEET RECORDS BELOW IS ACTUALLY AN 14-STRANDED BARREL THIS IS REPRESENTED BY A 15-STRANDED SHEET IN WHICH THE FIRST AND LAST STRANDS ARE IDENTICAL.