Notional Boiundary

C/AS1 clauses 5.1.2 and 5.1.1 (a) seem inconsistent with C/AS2 figure 5.2. My situation is as below. The 1.0m length walls in blue need to be fire-rated - since the angle is less than 90 degress to the notional boundary. Am I interpreting C/AS1 correctly? The walls are 135 degrees from each other.

I have seen people make the argument that when the angle is >90degrees, there is no requirement to draw a notional boundary, and therefore there is no requirement to provide fire rating.

Alternatively, if you were to draw a notional boundary, it would be possible to do it in such a way that the boundary runs along the external wall for 1m before bending away from the building, such that only one of the units is within 1.0m of the notional boundary rather than fire rating both units.

Thanks. it seems to me that the wording in C/AS1 is at odds with fire spread theory though.

Are they unit titled flats, so e.g. the property boundary continues in line with the dividing wall. Fire spread in that case is to the property title, not the other part of the building and you would have to project forward the unprotected area, which will set the length of the wing wall.