If you have process wastes in A1-A3 that have a value associated with them and have reached the end-of-waste state, they can be considered as co-products.
For example, if in the main product under study there is steel as a raw material which is cut to size during manufacturing, and the off-cuts are used in another product process or sold as scrap, co-product allocation may be applied depending on the mass and price of the main product and the co-product.
If process subdivision is not possible, allocation of co-products should be done using physical allocation or economic allocation.
The below excel document can be used to decide which allocation method, if any, should be used for your product life cycle assessment, and what allocation percentage to apply.
If you have any questions about using it, please don't hesitate to contact us.