def assign_caption(caption = nil, key = nil)
unless title? || @caption.nil?
return nil
end
if caption.nil?
if @document.attr?('caption')
@caption = @document.attr('caption')
elsif title?
key ||= @context.to_s
caption_key = "#{key}-caption"
if @document.attributes.has_key?(caption_key)
caption_title = @document.attributes["#{key}-caption"]
caption_num = @document.counter_increment("#{key}-number", self)
@caption = "#{caption_title} #{caption_num}. "
end
else
@caption = caption
end
else
@caption = caption
end
nil
end