diff --git a/src/workflow-design-guide/general-principles.rst b/src/workflow-design-guide/general-principles.rst
index b857cff482..93cd6a53a1 100644
--- a/src/workflow-design-guide/general-principles.rst
+++ b/src/workflow-design-guide/general-principles.rst
@@ -465,6 +465,8 @@ Sometimes it may be useful to refer to other cycles - to do this use
    mkdir -p "${SHARE_CYCLE_DIR_MINUS_P1D}"
    echo "I believe in ..." > "${SHARE_CYCLE_DIR_MINUS_P1D}/somefile"
 
+See ``isodatetime --help`` for usage instructions.
+
 .. versionadded:: 8.3.1
 
    ``$CYLC_WORKFLOW_SHARE_DIR`` and the ``isodatetime`` are designed to