Analyzed Layout and Text Object

ALTO is an open XML standard to describe OCR text and layout information of printed documents. It is often used with METS standard.

Structure

An ALTO file consists of three major sections as children of the root <alto> element:

• <Description> section contains metadata about the ALTO file itself and processing information on how the file was created.
• <Styles> section contains the text and paragraph styles with their individual descriptions:
  • <TextStyle> has font descriptions
  • <ParagraphStyle> has paragraph descriptions, e.g. alignment information
• <Layout> section contains the content information. It is subdivided into <Page> elements.

   <?xml version="1.0"?>
   <alto>
     <Description>
       <MeasurementUnit/>
       <sourceImageInformation/>
       <Processing/>
     </Description>
     <Styles>
       <TextStyle/>
       <ParagraphStyle/>
     </Styles>
     <Layout>
       <Page>
         <TopMargin/>
         <LeftMargin/>
         <RightMargin/>
         <BottomMargin/>
         <PrintSpace/>
       </Page>
     </Layout>
   </alto>

See also

• Metadata Encoding and Transmission Standard (METS)
• Dublin Core, an ISO metadata standard
• Preservation Metadata: Implementation Strategies (PREMIS)
• Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH)

External links

• ALTO (Analyzed Layout and Text Object) standards on Library of Congress website
• Slides about METS/ALTO by CCS GmbH
• ALTO Introduction by CCS GmbH