PER_SBU variable

In CropOntology web site I have looked at the "Pourcentage of sprouted bud" PER_SBU variable (CO_356:1000183) PER_SBU is classified under Biotic Stress class, Trait "Percentage of berries destroyed by Black rot Black" (CO_356:2000108) As far as I understand this variable it should be classified in Phenological class, Trait "Percentage of sprouted buds" (CO_356:2000120) This variable should be associated to a method like visual estimation or manual counting. The variable should be associated to a definition like "the variable as a phenological variable that returns the percentage of sprouted buds in a single plant. The method used is a manual counting of the total number of buds and a visual estimation is made to classify the buds in two sets buds that reach the BBCH stage 005 or ..."