When we change quantity value from 2 to 0 in item line level history it will shown that value changes from -2 to 0.
When we change quantity value from 1 to 2 in item line level history it will shown that value changes from -1 to -2.
When we change quantity value from 0 to 1 in item line level history it will shown that value changes from 0 to -1.
When we change quantity value from 1 to 0 in item line level history it will shown that value changes from -1 to 0.
ie, in item line level history quantity is represented by negative of the actual value.
