diff --git a/core/sources/constants.py b/core/sources/constants.py
index 9e48db24d..fc22d0189 100644
--- a/core/sources/constants.py
+++ b/core/sources/constants.py
@@ -7,3 +7,9 @@
 CONTENT_REFERRED_PRIVATELY = 'Could not delete source "{}". One or more resources in the source are ' \
                              'referenced by private repositories. Contact an OCL administrator for more information.'
 HIERARCHY_ROOT_MUST_BELONG_TO_SAME_SOURCE = 'Hierarchy Root must belong to the same Source.'
+HIERARCHY_MEANINGS = (
+    ('grouped-by', 'grouped-by'),
+    ('is-a', 'is-a'),
+    ('part-of', 'part-of'),
+    ('classified-with', 'classified-with'),
+)
diff --git a/core/sources/migrations/0018_auto_20210417_0430.py b/core/sources/migrations/0018_auto_20210417_0430.py
new file mode 100644
index 000000000..c70b4acf9
--- /dev/null
+++ b/core/sources/migrations/0018_auto_20210417_0430.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.1.8 on 2021-04-17 04:30
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('sources', '0017_source_hierarchy_root'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='source',
+            name='hierarchy_meaning',
+            field=models.CharField(blank=True, choices=[('grouped-by', 'grouped-by'), ('is-a', 'is-a'), ('part-of', 'part-of'), ('classified-with', 'classified-with')], max_length=50, null=True),
+        ),
+    ]
diff --git a/core/sources/models.py b/core/sources/models.py
index 3488ee32d..ad5f923d6 100644
--- a/core/sources/models.py
+++ b/core/sources/models.py
@@ -8,7 +8,8 @@
 from core.common.models import ConceptContainerModel
 from core.common.utils import reverse_resource, get_query_params_from_url_string
 from core.concepts.models import LocalizedText
-from core.sources.constants import SOURCE_TYPE, SOURCE_VERSION_TYPE, HIERARCHY_ROOT_MUST_BELONG_TO_SAME_SOURCE
+from core.sources.constants import SOURCE_TYPE, SOURCE_VERSION_TYPE, HIERARCHY_ROOT_MUST_BELONG_TO_SAME_SOURCE, \
+    HIERARCHY_MEANINGS
 
 
 class Source(ConceptContainerModel):
@@ -44,7 +45,7 @@ class Meta:
     source_type = models.TextField(blank=True, null=True)
     content_type = models.TextField(blank=True, null=True)
     collection_reference = models.CharField(null=True, blank=True, max_length=100)
-    hierarchy_meaning = models.CharField(null=True, blank=True, max_length=50)
+    hierarchy_meaning = models.CharField(null=True, blank=True, max_length=50, choices=HIERARCHY_MEANINGS)
     case_sensitive = models.BooleanField(null=True, blank=True, default=None)
     compositional = models.BooleanField(null=True, blank=True, default=None)
     version_needed = models.BooleanField(null=True, blank=True, default=None)