diff --git a/v1/preface.xml b/v1/preface.xml
index a44cdb9..6512f0b 100644
--- a/v1/preface.xml
+++ b/v1/preface.xml
@@ -67,7 +67,8 @@ format="SVG" scale="60"/>
RESTful web services
- HTTP/1.1
+ HTTP/1.1 - the Swift API is HTTP 1.1, which means that you can use cache
+ control headers such as If-Modified-Since in your queries.
You can also find language-specific APIs in several