diff --git a/base_classes/NXmonochromator.nxdl.xml b/base_classes/NXmonochromator.nxdl.xml
index 91e5ec7b30..5c03d3a39d 100644
--- a/base_classes/NXmonochromator.nxdl.xml
+++ b/base_classes/NXmonochromator.nxdl.xml
@@ -68,6 +68,8 @@
Use as many crystals as necessary to describe
+ Use as many mirrors as necessary to describe
+ Use as many slits as necessary to describe
For diffraction grating based monochromators