What makes a landing good?

• The rule: it is a failure if the discus "in contacting the ground when it first lands touches the sector line or the ground outside the sector line".
• The sector: two white lines 50 mm wide at an angle of 34.92 degrees. Their inner edges, if extended, would pass through the centre of the circle.
• How wide that is: 20 m from the centre of the circle the lines are 12 m apart. For every metre further out, the sector is 0.60 m wider.
• Each line is out: the inner edge of each sector line is the boundary. A landing that touches the line is a failure.
• First landing only: the rule looks at where the discus first meets the ground. A bounce, roll or slide afterwards is not judged.
• Hitting something on the way: since 2026 it is also a failure if the discus touches any object outside the sector line after release and before it lands, other than the cage.
• The far side of the cage: it is a failure if the discus strikes the far side of the cage after release. For a right-handed thrower facing the sector that is the left side, and for a left-hander the right.
• The near side of the cage: it is not a failure if the discus strikes the near side of the cage after release and then lands inside the sector, beyond the limits of the cage.
• The limits of the cage: the netting and its gates, closed off by an imaginary straight line between the two ends nearest the sector.
• The ground: grass, cinders or another surface on which the implement leaves a mark.
• The signal: a judge near the landing shows a throw that is out of the sector by holding an arm out.

The sector is where the judges stand ready and nobody else is allowed, so a throw outside it is a danger as well as a miss. Counting the line as out gives one clear test: the mark is either wholly inside or it is not. The cage rule separates a discus that was pulled wide into the netting from one that brushed the netting on its way down the sector.