SB, don't panic. I think (but don't know 100%) that these are the maximum dimensions for each of length, height and width when considered individually. The overall (and overriding limit) is the sum which cannot exceed 115.

So, for example, you couldn't have a suitcase with the following dimensions:

L 60, H 40 and W 10 = 110 (sum OK), because L exceeds maximum of 56 (not OK)


The text could be better written as something like:

The maximum allowable sum of L+W+D is 115cm, with a further restriction that none of the individual dimensions of L, H and W can exceed 56, 46 and 25 respectively.

For those of you wanting a legal case, with the maximum volume, it should have the following dimensions 45+45+25 = 115 linear and has volume = 50.6 litres. If the W limitation of 25cm was removed, the dimensions should be 38x38x38 = 114 and has volume 54.9 litres.

I think a skinnier case is more practical!!