Claiming is pointing read in the other direction. Pointing starts inside a box and eliminates along a row or column; claiming starts along a row or column and eliminates inside a box. Same underlying idea — a digit locked to the intersection of a line and a box — approached from the opposite side.

What “claiming” means

Look along a single row (or column). If a digit’s remaining candidates in that row all fall inside the same box, the row has “claimed” that digit for that box — it must go somewhere in that intersection, which means every other cell in the box, outside the row, can have it eliminated.

Worked example

5
6
9
3
47
47
2
1
8
18
3
4
1589
19
2
79
579
6
18
7
2
15689
169
169
349
459
349
3
1
6
49
2
8
479
479
5
7
9
5
146
3
146
8
2
14
4
2
8
7
5
19
139
6
139
2
5
37
1469
14679
134679
14679
8
1479
6
4
37
2
8
1379
5
79
179
9
8
1
46
467
5
467
3
2

In column 9, 7 only appears inside box 9, so it can be removed from the rest of that box.

Here the eliminations land inside a box, on cells that aren’t part of the row or column at all. That’s the tell for telling claiming apart from pointing at a glance: pointing clears cells along a line; claiming clears cells inside a box.

How to find one quickly

Scan a row with several digits still open. For each digit, check which cells in the row could still take it. If they’re all in the same box, look at the rest of that box — the cells outside the row — and cross that digit off anywhere it still appears there.

Run this alongside pointing — they apply to the same kind of situation from opposite directions, and a thorough pass checks both before moving on to naked pairs or hidden pairs.

Puzzles at Medium are the first level built around needing this.