+=head1 OPTIONAL ARGUMENTS
+
+Some commands take optional arguments. These arguments appear in this
+documentation as C<[argname:..]>. You can use them as in these
+examples:
+
+ add-drive-opts filename
+
+ add-drive-opts filename readonly:true
+
+ add-drive-opts filename format:qcow2 readonly:false
+
+Each optional argument can appear at most once. All optional
+arguments must appear after the required ones.
+