If I had numbers 1-10 in an attribute table and sorted by this field the number 10 would be placed between 1 and 2. Logically it should come after 9. If I had the lower-case letters a-z, and upper-case A-Z in another field and sorted by that, the letters we be ordered as A,B,C...Z,a,b,c...z. In the real world 'a' comes before 'Z' regardless of case.
The same sorting is used in catalog, its ilogical there too.
My idea is that the sorting algorithm is reengineered to be more logical.