# File lib/docbook.rb, line 22
    def initialize(docbook_file, output_dir=OUTPUT_DIR, css_file=nil, customization_layer=nil, embedded_fonts=[])
      @docbook_file = docbook_file
      @output_dir = output_dir
      @meta_dir  = File.join(@output_dir, META_DIR)
      @oebps_dir = File.join(@output_dir, OEBPS_DIR)
      @css_file = css_file ? File.expand_path(css_file) : css_file
      @embedded_fonts = embedded_fonts
      @to_delete = []
      
      if customization_layer
        @stylesheet = File.expand_path(customization_layer)
      else
        @stylesheet = STYLESHEET
      end

      unless File.exist?(@docbook_file)
        raise ArgumentError.new("File #{@docbook_file} does not exist")
      end
    end