Select field descriptive or numeric keys I have created a field of type List (text) with widget Select list.
After editing most of its settings, it came to complete its Allowed values list.
Following the help's text instructions, the values should have this form key|label and here is my question: 

Should I use descriptive or numeric keys for the values (and why)? 


  The key is the stored value


Does this (keys) selection will have any impact in the future if for example I want to use these values for aggregation (with views or not)?
The key|label format is for scenarios where you want to present a different, user-friendly, label that differs from the underlying, machine-readable, storage. For example, a country select list that you want represent in the 2-character ISO 3166-1 format while showing the official country names to present to the user selecting it.

In the above scenario, regardless of using the key|label format or not, the underlying data will be represented as a string (VARCHAR) since it's a Field (text) field type. If your underlying data needs to be represented as numeric, then you should use the List (Integer) (or other number types) field type as it will be stored as INT within the DB column.