Just to chip in on the discussion on waste and waste treatment activities:
- The problem that a service activity often has the same name as the service that it provides is a well-known problem. It is not solved by inventing new speculative unique names, but rather by linking the instances of the names to their classes (activity or flow-object).
- Principle: We try to avoid making fixed choices, like sign nomenclatures, that are only useful in specific contexts.
- Principle: It is a good practice for a model to stay as close to reality as possible
- Principle: Do not introduce unneccesary (obligatory) classifications
- Wastes, by-products and emissions do not need to be distinguished. Following the physical reality, they are all just non-determining output flows of the activity that produces them and determining input flows to the activity that is activated by their prescence (waste treatment for wastes, recycling activities for by-products for treatment, markets for by-products that do not need treatment, ecological fate activities for emissions). The fact that some calculations require that non-determining outputs are calculated as negative inputs does not mean that the database needs to use such artificial conventions.