Accession: title to additions or annexed goods depends on timing and reservation of security interests. The concept of accession denotes acquisition of title to additions to property by natural growth or human labour, including annexation of chattels to a principal thing and additions to land by alluvion or improvements. Competing proprietary or secured interests over accessions depend on whether a security interest was reserved at the time of installation or acquired later; a reserved security interest may allow removal of the accession, while earlier perfected interests may prevail where no prior reservation exists.