core/modules/edit/edit.module |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/core/modules/edit/edit.module b/core/modules/edit/edit.module
index 4b462e8..059271c 100644
--- a/core/modules/edit/edit.module
+++ b/core/modules/edit/edit.module
@@ -179,7 +179,8 @@ function edit_preprocess_field(&$variables) {
   $entity = $element['#object'];
 
   // Edit module only supports view modes, not dynamically defined "display
-  // options" (which always result in the "_custom" view mode).
+  // options" (which field_view_field() always names the "_custom" view mode).
+  // @see field_view_field()
   // @see https://drupal.org/node/2120335
   if ($element['#view_mode'] === '_custom') {
     return;