Paper and screen are two different presentation media. For example, the concept of fixed length pages does not apply to the screen. It is much more natural to group the information in chapters, per subject. Also, when expressed in pixels, a good computer screen has half the size of an A4 paper. For the text to remain readable, the length of a text in a table cell has to be reduced at least by one third.
Presenting the information on screen has different constraints from presenting the same information on paper. XML and HTML are Web technologies, developed specifically with the aim to make information available on computer screens. The on-screen (HTML) presentation part of the eAIP Specification is based on the conclusions of a User Requirements and Usability Guidelines, performed under contract for EUROCONTROL by Helios Technology, UK. The study included a validation workshop with a group of real users.
The requirements identified through this study have been characterised as ‘inherited’ requirements or ‘functional’ requirements:
inherited requirements are those deriving from the ICAO SARPS specified in Annex 15, such as:
the eAIP structure and layout must adhere to the requirements for presentation as set out by ICAO;
the update cycle of the eAIP must adhere to the AIRAC cycle requirements;
all Amendments (alterations, additions and deletions) made to the eAIP in the last AIRAC cycle must be indicated.
functional requirements are those deriving from the transition from paper-based to electronic media, such as:
the Table of Contents is the main navigation tool into the eAIP document; it must be simple, fast and effective to use;
where Amendments modify text, there must be some provision for comparing the previous and modified versions;
‘live access’ versions of the eAIP (e.g. Web sites) should incorporate the core AIP (GEN, ENR, AD) and all accompanying documents (AMDTs, SUPs, AICs, NOTAMs);
‘disseminated’ versions (for example, CDs) will exclude NOTAMs, but must incorporate links to NOTAMs on a live website;
it must be possible to verify the date on which each section became effective, and the source of the information if relevant;
cross-references within the body of the text (e.g. ‘See section …’) will be implemented as links
charts in the eAIP must be scalable, zoom-able and display configurable content.
The full results of the study are available in the User Requirements and Usability Guidelines document. Not all requirements identified by the study are supported by the current eAIP browsing stylesheets. In particular, requirements that refer to advanced search facilities are not supported yet (for example: "the eAIP must have a facility for searching for all instances of a given word in the body of the AIP, and accompanying documents. The search results will have links into the appropriate sections of the body of the document").
However, such requirements do not affect the eAIP DTD structure, but rather the functionality offered by the stylesheets. It is expected that such requirements could be fulfilled by integrating the eAIP into an XML/HTML document management system.