Multiples of 9

9, 18, 27, 36, 45, 54, 63, 72, 81, 90

What is the pattern?

9, 1+8, 2+7, 3+6, 4+5, 5+4, 6+3, 7+2, 8+1, 9+0

9, 9, 9, 9, 9, 9, 9, 9, 9, 9

The numbers are odd, even, odd, even and sum of all the digits add to 9. They form a diagonal on the 100's block.