diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
index b8a77e1fa0..5e1a381fac 100644
--- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
+++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
@@ -293,6 +293,17 @@
The flags are immediately set to "abc" and "123", respectively.
The a flag becomes "abc456".
+
+
+ No need exists to pre-define variable flags.
+ You can simply start using them.
+ One extremely common application
+ is to attach some brief documentation to a BitBake variable as
+ follows:
+
+ CACHE[doc] = "The directory holding the cache of the metadata."
+
+
@@ -306,7 +317,19 @@
DATE = "${@time.strftime('%Y%m%d',time.gmtime())}"
This example results in the DATE
- variable becoming the current date.
+ variable being set to the current date.
+
+
+
+ Probably the most common use of this feature is to extract
+ the value of variables from BitBake's internal data dictionary,
+ d.
+ The following lines select the values of a package name
+ and its version number, respectively:
+
+ PN = "${@bb.parse.BBHandler.vars_from_file(d.getVar('FILE'),d)[0] or 'defaultpkgname'}"
+ PV = "${@bb.parse.BBHandler.vars_from_file(d.getVar('FILE'),d)[1] or '1.0'}"
+