Traits are user created variables to register Measurements for Individuals, Vouchers, Locations and/or Taxons. These user defined variables are shared in a ODB installation and their definition cannot be modified nor deleted if they are in use for some Measurements, unless the User is the administrator of such measurements. Because it is a shared library, Trait definition must be as precise as possible, and the creation of new variables should be made with great attention as to maximize standardization, avoiding unecessary redundancy.