diff --git a/etc/accounts.yaml.sample b/etc/accounts.yaml.sample
index decc659..3dbed79 100644
--- a/etc/accounts.yaml.sample
+++ b/etc/accounts.yaml.sample
@@ -3,7 +3,25 @@
 # This is required to provide isolation between test for running in parallel
 #
 # Valid fields for credentials are defined in the descendants of
-# auth.Credentials - see KeystoneV[2|3]Credentials.CONF_ATTRIBUTES
+# lib.auth.Credentials - see KeystoneV[2|3]Credentials.ATTRIBUTES
+#
+# The fields in KeystoneV3Credentials behave as follows:
+#
+# tenant_[id|name] also sets project_[id|name].
+#
+# project_[id|name] also sets tenant_[id|name].
+#
+# Providing distinct values for both tenant_[id|name] and project_[id|name]
+# will result in an InvalidCredentials exception.
+#
+# The value of project_domain_[id|name] is used for user_domain_[id|name] if
+# the latter is not specified.
+#
+# The value of user_domain_[id|name] is used for project_domain_[id|name] if
+# the latter is not specified.
+#
+# The value of domain_[id|name] is used for project_domain_[id|name] if not
+# specified and user_domain_[id|name] if not specified.
 
 - username: 'user_1'
   tenant_name: 'test_tenant_1'