I am look to do an Offset of something like a offset. I level data in
column "A" and Part Number in Column "B". What I need to do is look
at the level data for "1, 2, 3, 4, ets." Then lookup the table for the
first value that is equal to data -1 and report out the Part Number
from its column "B".

Data
A B
1 P1
2 P2
3 P3
3 P4
4 P5

Results
A B C
0 P
1 P1 P
2 P2 P1
3 P3 P2
3 P4 P2
4 P5 P4