diff --git a/app/code/local/Df/Core/lib/array/clean/filter.php b/app/code/local/Df/Core/lib/array/clean/filter.php
index a5797b72a2..3f22bc6a92 100644
--- a/app/code/local/Df/Core/lib/array/clean/filter.php
+++ b/app/code/local/Df/Core/lib/array/clean/filter.php
@@ -11,9 +11,11 @@
  * 2020-02-05 Now it correcly handles non-associative arrays.
  * 2024-03-03 "Port `df_filter()` from `mage2pro/core`": https://github.com/thehcginstitute-com/m1/issues/452
  * 2024-06-03
- * 1) "Use the `iterable` type": https://github.com/mage2pro/core/issues/403
- * 2) `iterable` is supported by PHP ≥ 7.1: https://3v4l.org/qNX1j
- * 3) https://php.net/manual/en/language.types.iterable.php
+ * 1.1) "Use the `iterable` type": https://github.com/mage2pro/core/issues/403
+ * 1.2) `iterable` is supported by PHP ≥ 7.1: https://3v4l.org/qNX1j
+ * 1.3) https://php.net/manual/en/language.types.iterable.php
+ * 2) We still can not use «Union Types» (e.g. `callable|iterable`) because they require PHP ≥ 8 (we need to support PHP ≥ 7.1):
+ * https://php.watch/versions/8.0/union-types
  * @used-by df_clean_r()
  * @param callable|iterable $a1
  * @param callable|iterable $a2