You can define the substances and the amounts emitted during decommission of the part.
In the Built-in Product Emissions section you estimate how much of the built in substances that will be discarded as waste at the end of the life time of a specific product. You need to calculate emissions for the part first. Only the substances with emission media code defined as Product, Recycling or Reuse show up in this section. A good example could be a battery which contains lead. When the battery is broken or has reached its end of the life time then must this substance be recycled. Another example could be a soft drink bottle of aluminum. When its content is consumed then is the product itself an end of life emission which must be recycled in order to be reused.
In the Additional Emissions section you define the substances and the amounts emitted during decommission of the part. An example of an additional end of life emission could be emissions (for instance CO2) emitted when compressing a car at an old car dump and/or when moving the compressed car to its final destination before recycling of the chassis. Another example could be emissions related to a dismantling of an old gas station taken out of order.