Change record status: 
Project: 
Introduced in branch: 
8.x
Introduced in version: 
8.0
Description: 
  • 3 new constants have been added to describe the taxonomy hierarchy :
    • TAXONOMY_HIERARCHY_DISABLED: Denotes that no term in the vocabulary has a parent.
    • TAXONOMY_HIERARCHY_SINGLE: Denotes that one or more terms in the vocabulary has a single parent.
    • TAXONOMY_HIERARCHY_MULTIPLE: Denotes that one or more terms in the vocabulary have multiple parents.
  • Modules should use these new constants instead of the previous integer values beginning with Drupal 8. The mapping table is as the following :
Old integer value New constant name
0 TAXONOMY_HIERARCHY_DISABLED
1 TAXONOMY_HIERARCHY_SINGLE
2 TAXONOMY_HIERARCHY_MULTIPLE
Impacts: 
Module developers