def base_content_types
      c_types = ContentType.new()
      c_types << Default.new(:ContentType => RELS_CT, :Extension => RELS_EX)
      c_types << Default.new(:Extension => XML_EX, :ContentType => XML_CT)
      c_types << Override.new(:PartName => "/#{APP_PN}", :ContentType => APP_CT)
      c_types << Override.new(:PartName => "/#{CORE_PN}", :ContentType => CORE_CT)
      c_types << Override.new(:PartName => "/xl/#{STYLES_PN}", :ContentType => STYLES_CT)
      c_types << Axlsx::Override.new(:PartName => "/#{WORKBOOK_PN}", :ContentType => WORKBOOK_CT)
      c_types.lock
      c_types
    end
def base_content_types
      c_types = ContentType.new()
      c_types << Default.new(:ContentType => RELS_CT, :Extension => RELS_EX)
      c_types << Default.new(:Extension => XML_EX, :ContentType => XML_CT)
      c_types << Override.new(:PartName => "/#{APP_PN}", :ContentType => APP_CT)
      c_types << Override.new(:PartName => "/#{CORE_PN}", :ContentType => CORE_CT)
      c_types << Override.new(:PartName => "/xl/#{STYLES_PN}", :ContentType => STYLES_CT)
      c_types << Axlsx::Override.new(:PartName => "/#{WORKBOOK_PN}", :ContentType => WORKBOOK_CT)
      c_types.lock
      c_types
    end
Creates the minimum content types for generating a valid xlsx document.
 @return [ContentType]
 @private