The saxon:mode element is a top-level element.
It is used to define properties of a mode, in particular whether the mode is streamable.
The name attribute indicates the name of the mode (which will normally match the
mode attribute of one or more template rules. Specifying name="#default"
is equivalent to omitting the attribute, and indicates that the declaration applies to the default (unnamed) mode.
The streamable attribute takes the value yes or no,
default no. If yes is specified, all template rules in this mode
must be streamable templates, and all processing using these template rules is done using streaming.
This declaration is available only in Saxon-EE.
