diff --git a/guide/reference/api/index.textile b/guide/reference/api/index.textile
index f7ae2e44f..675bf8b38 100644
--- a/guide/reference/api/index.textile
+++ b/guide/reference/api/index.textile
@@ -32,3 +32,4 @@ p. All REST APIs accept the @case@ parameter. When set to @camelCase@, all field
 h2. JSONP
 
 p. All REST APIs accept a @callback@ parameter resulting in a "JSONP":http://en.wikipedia.org/wiki/JSONP result.
+p. You can also use the @source@ query string parameter to substitute for the body of the request.