The EUROCONTROL eAIP is a specification for the publication and exchange of the Aeronautical Information Publication in electronic format.
Specification: the eAIP defines an electronic format and the general usage process
Publication: the eAIP is designed to be published, be it on screen or on paper and used by people;
Exchange: to a certain extent, the eAIP can be used for computer-to-computer data exchange. However, the eAIP Specification does not offer the same capabilities for structured aeronautical data exchange as the Aeronautical Information Exchange Model (AIXM).
The essential difference between the two is that AIXM models the aeronautical information, while the eAIP models the AIP document. AIXM is primarily intended for computer-to-computer aeronautical data exchange. The eAIP is primarily intended to provide the AIP content for publication in various formats and on various media, according to user needs.
The EUROCONTROL eAIP is based on XML (eXtensible Mark-up Language). An electronic AIP is in fact an XML document, conforming to the eAIP DTD.
The eAIP in XML is transformed into other formats using XSLT:
for on-screen display, the eAIP is transformed into HTML (Hyper-Text Mark-up Language);
when paper is the target, the eAIP is transformed into XSL-FO. Software tools must be used to print XSL-FO. Currently, the most convenient method is to first convert XSL-FO to PDF or PostScript and then print those files.
Charts and graphics can be in various formats, and a very interesting one for aeronautical charts is Scalable Vector Graphics (SVG). All these technologies are official recommendations (standards) published by the W3C (World Wide Web Consortium).
XML stands for eXtensible Mark-up Language. XML is a subset of the Standard Generalized Markup Language (SGML, ISO 8879). Since 1998, when it was published as a recommendation by the World Wide Web Consortium (W3C), XML has rapidly become the de-facto industry standard for electronic data interchange.
XML is a meta-language (a language to define other languages). It allows us to define an "AIP language" for computers. Using the EUROCONTROL eAIP language, people and computers can talk to each other using the same vocabulary and grammar.
XML has been chosen because it fulfils the eAIP's main objective: it is commonly used for structuring documents and it is suitable for both human to computer and computer to computer interactions. Also, it is a recognised standard since 1998, widely adopted by the software developers in many industries.
DTD stands for Document Type Definition. It is a formal representation of XML documents' structure. To keep up with our previous analogy with languages, the eAIP DTD is a formal definition of the eAIP language vocabulary and grammar.
XSLT stands for eXtensible Stylesheet Language Transformations. It is an XML-based language that allows to transform an XML document into another XML document (or into text document as well). In the eAIP context, XSLT is used to convert eAIP files from XML into HTML format or XSL-FO format.
XSL-FO stands for eXtensible Stylesheet Language Formatting Objects. It is an XML-based language that allows to express a document with its formatting, for example to print it on paper. In the eAIP context, XSL-FO is used to format an eAIP in order to print it on paper. With adequate software, it will be possible in future to directly print an XSL-FO document. In the mean time, it is possible to use software that convert XSL-FO to PDF or PostScript and then print those files.
SVG stands for Scalable Vector Graphics. It is an XML-based language to express 2-dimensional drawings using simple graphical objects such as lines, circles, rectangles and text, and object properties such as color, size and position. Being written in XML, SVG charts can quite easily be linked to other XML information.
It is possible to zoom into a small portion of an SVG image and still see a very precise definition of the image. In fact, SVG image resolution is only limited by printers' resolution. SVG images can be interactive; for example, it is possible to highlight a single route on route map or click on an object on a map and get additional information about this object.
This diagram shows the default eAIP production process from XML production to HTML and paper AIP publication. Technologies used on this process are mentioned as well.
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The advantage of this process is that the both the browsing format and the printing format are generated from the same XML files, which can be made available to the user.
It is also possible that both the XML files and the printing format (PDF) are produced from another source. Structured text editors, such as Adobe FrameMaker, are able to produce export files both in PDF and in XML format. The advantage of such an alternate process is that the generation of the PDF files is straight-forward, as done by the editing tool.
On the other side, the XML export process is usually embedded into the software tool and the editors do not have much control over it. Therefore, the editors must ensure at every issue that there are no discrepancies between the XML/HMTL content on one side and the PDF content on the other side. The users do not have access to the original file sources which were use to produce the XML and PDF format.
The eAIP Specification software, including the DTD (document type definition), the source code and documentation is provided under a specific Open Source license. Please read the file LICENSE.txt in the eAIP package, or the license section in this document, for more details. You can find more information on Open source Software licensing at the Open Source Initiative organisation.
| This software is OSI Certified Open Source Software. OSI Certified is a certification mark of the Open Source Initiative. |
The full eAIP package is bundled with the following Open Source Software:
SAXON XSLT Processor by Michael Kay
Schematron 1.5 tools by David Carlisle and Rick Jelliffe (modified for the eAIP)
Xerces XML Parser by the Apache Software Foundation
XHTML Modularization by the World Wide Web Consortium
OpenSSL by The OpenSSL Project
GPG by the Free Software Foundation
They are re-distributed with permission, following their respective license. Please read the file LICENSE.txt in the eAIP package, or the license section in this document, for more details.