Two special 'bind-only' datatypes were added, EXTENDED TIMESTAMP WITH TIME ZONE and EXTENDED TIME WITH TIME ZONE. These types are the same as their 'normal' WITH TIME ZONE counterpart, with the difference that they have an extra signed short (serialized as 4 bytes in the wire protocol) with the offset in minutes, which is populated for both offset and named zone values.
The support in Jaybird will be minimal: we will parse the value exactly the same as the 'normal' WITH TIME ZONE types, basically ignoring the extra bytes. On sending the values, these bytes will always be zeroed. This support is intended to address situations where users manually set the bind to an extended type.