diff --git a/rest_framework/schemas/openapi.py b/rest_framework/schemas/openapi.py
index eb4528df7..1db20a9d4 100644
--- a/rest_framework/schemas/openapi.py
+++ b/rest_framework/schemas/openapi.py
@@ -218,6 +218,7 @@ class AutoSchema(ViewInspector):
         elif all(isinstance(choice, int) for choice in choices):
             type = 'integer'
         elif all(isinstance(choice, (int, float, Decimal)) for choice in choices):  # `number` includes `integer`
+            # SEE: https://tools.ietf.org/html/draft-wright-json-schema-validation-00#section-5.21
             type = 'number'
         elif all(isinstance(choice, str) for choice in choices):
             type = 'string'