doc: allow layers to ignore pAllocator
diff --git a/loader/LoaderAndLayerInterface.md b/loader/LoaderAndLayerInterface.md
index 8414386..7821347 100644
--- a/loader/LoaderAndLayerInterface.md
+++ b/loader/LoaderAndLayerInterface.md
@@ -1115,6 +1115,11 @@
lower layers never see the wrapping objects, directly from itself or
indirectly from its upper layers.
+When a layer requires host memory, it may ignore the provided allocators. It
+should use memory allocators if the layer is intended to run in a production
+environment, such as an implicit layer that is always enabled. That will
+allow applications to include the layer's memory usage.
+
`vkEnumerateDeviceExtensionProperties` must handle the case where `pLayerName`
is `NULL`, usually by chaining to other layers.