Review of the existing values that have been used by various establishments shows that there are some overlapping concepts.
Therefore, it would be wise to create a separate term called 'preservation method'.
There is also the question of 'sub-sampling' where one piece of material (a 'sample' from the field) enters the lab and is then divided into more than one entity for analysis and storage. For example, an insect might be partially dissected to create a slide of genitalia, along with the rest of the individual insect.
This is not captured so far.