diff --git a/doc_src/index.hdr.in b/doc_src/index.hdr.in
index 5c8be9a4d..51f021d64 100644
--- a/doc_src/index.hdr.in
+++ b/doc_src/index.hdr.in
@@ -771,6 +771,9 @@ Variables can be explicitly set to be exported with the `-x` or `--export` switc
 
 -# If a variable is not explicitly set to be either exported or not exported and has never before been defined, the variable will not be exported.
 
+-# If a variable has local-scope and is exported, any function called receives a _copy_ of it, so any changes it makes to the variable disappear once the function returns.
+
+-# If a variable has global-scope, it is accessible read-write to functions whether it is exported or not.
 
 \subsection variables-arrays Arrays