I'm trying to understand the following table in terms of colouring. I realise this is specific to a particular product but a lot of other products seem to use red, blue, black as a color code scheme as well so hopefully it translates.

My first impression is that red means negative, blue means positive and black means no change. But what is it comparing? For instance in the table above:
GBP/CHF the net change column is a blue +1 so i might assume that this net change column means the buy price is +1 over the high.
However this rule breaks quickly when comparing to any other row say GBP/JPY.
So im not sure of the relationships between the data what Im looking at and how it is subsequently expressed in colour.