class Builder::XmlMarkup

def instruct!(directive_tag=:xml, attrs={})

rather than the entity encoding normally used.
$KCODE is "UTF8", then builder will emit UTF-8 encoded strings
Note: If the encoding is setup to "UTF-8" and the value of

#=>
xml.instruct! :aaa, :bbb=>"ccc"
#=>
xml.instruct!

For example:

Insert a processing instruction into the XML markup. E.g. 
def instruct!(directive_tag=:xml, attrs={})
  _ensure_no_block ::Kernel::block_given?
  if directive_tag == :xml
    a = { :version=>"1.0", :encoding=>"UTF-8" }
    attrs = a.merge attrs
coding = attrs[:encoding].downcase
  end
  _special(
    "<?#{directive_tag}",
    "?>",
    nil,
    attrs,
    [:version, :encoding, :standalone])
end