1. The Core Objective: "The Carbon Ledger"

The goal is to calculate a company’s **Carbon Footprint** (measured in CO_2e — Carbon Dioxide Equivalent). To do this, the system must follow a standard (usually the GHG Protocol).

The engine performs a simple but massive math operation:
$$\text{Activity Data (e.g., Liters of Diesel)} \times \text{Emission Factor (EF)} = \text{Carbon Footprint}$$

The Challenge for your Architecture:

The "Activity Data" comes from the user (CSV), but the **Emission Factors** are massive, regulated databases (like DEFRA, EPA, or IPCC) that change every year and vary by country. Your engine has to map the user's "Diesel" to the _correct_ factor for their specific region and year.