diff --git a/documentation/ref-manual/closer-look.xml b/documentation/ref-manual/closer-look.xml
index 7546215ae6..f0ed967228 100644
--- a/documentation/ref-manual/closer-look.xml
+++ b/documentation/ref-manual/closer-look.xml
@@ -713,8 +713,19 @@
do_fetch
and
do_unpack
- tasks fetch the source files
- and unpack them into the work directory.
+ tasks fetch the source files and unpack them into the work
+ directory.
+
+ For every local file (e.g. file://)
+ that is part of a recipe's
+ SRC_URI
+ statement, the OpenEmbedded build system takes a checksum
+ of the file for the recipe and inserts the checksum into
+ the signature for the do_fetch.
+ If any local file has been modified, the
+ do_fetch task and all tasks that
+ depend on it are re-executed.
+
By default, everything is accomplished in the
Build Directory,
which has a defined structure.