diff --git a/doc/support.md b/doc/support.md
index 50196d2..350d77b 100644
--- a/doc/support.md
+++ b/doc/support.md
@@ -421,3 +421,14 @@ the evaluation. If the test passes, prints "." like all tests from
 this module do.
 
 ### Environment
+
+    (import environment)
+
+Basic UNIX environment support.
+
+    (edit-file file-path)
+
+* ```file-path``` - path to file to edit
+
+Runs the editor specified by the environment variable EDITOR or - if
+unset - the editor binary.