Accession: "An increase by means of something added to record as acquired" - Websters. Accessioning is the act of taking on the responsibility to perform a laboratory test and adding the test to the laboratory's workload (hence the word accession, the workload or responsibility has been increased). While the definition would imply a close alignment with the Lab Test Promise, in practice, the Accession (and the "Accession Number") are more closely associated with the Specimen, as the Specimen represents a unit of work. Accession numbers and specimen numbers are often related, and when a specimen is subsetted for some other purpose, a new accession number may be created. This class represents the act of creating a new accession, and is associated with both the Promise and the Specimen.