diff --git a/doc/manual.adoc b/doc/manual.adoc
index 34744c0..6df90b6 100644
--- a/doc/manual.adoc
+++ b/doc/manual.adoc
@@ -85,6 +85,11 @@ The Python 3 expression is evaluated and placed in the field when creating a new
 record.  This can be used, for example, to automatically insert the date into a
 particular field.
 
+==== Key Field Directives (`key`)
+
+Key field directives indicate the fields to display in the _Browse All Records_
+view.  By default, this value is 0 (display the first field).
+
 === Configuration File
 
 Configuration files are identical to schema files except that instead of the