But how to convert the list in a specific format and for a specific purpose (e.g. organize the activities and flows in B matrix + square A matrix to be used in the g = BA^{-1}f calculation for LCA) remains outside the scope of this ontology. This conversion should be regarded as a separate step. One would have to develop another additional ontology on top of the base one, or using some additional information external to the ontology like a list specifying what are the biosphere flows, or make other additional assumptions and choices like deciding which of two output flows is the determining one and applying one or another method to solve multifunctionality.

We will be able to talk about this soon in person, which should be helpful as we might be going a bit in circles. In any case, here are my contributions to the dance:

1. Identifying potential biosphere flows is relatively easy - they are either only consumed and never produced, or vice versa. We can debate if this is enough, or even fits into our logical sense of how we want to build the model, but if we want to make a solvable linear algebra problem it is enough. Think about the *purpose* of separating the A and B matrices. 2. A square technosphere matrix is an output of one possible system model, but is not required. Some system models will not produce square matrices, and other approaches will use graph traversal and not use matrices at all. 3. Our database is not only used for matrix-based LCA, but also e.g. MFA, so should not be too specific to what you read in an LCA textbook. This has already been said before by multiple people, but is worth repeating :)