The A2A database contains nearly 100,000 catalogues - nearly 10 million records - describing archives held in more than 400 repositories throughout England and Wales and dating from the eighth century to the present day.
An online ASP application utilises TEXTML Server native XML indexing / retrieval software and delivers temporary HTML pages derived on-the-fly from XML using XSLT (via the MSXML engine).
3 HTML views of each catalogue are available in the main application (derived through 3
different XSLT stylesheets):
"Hits in Context" - the default HTML view following a
Keyword search.
"Full Catalogue" - the default HTML view following a non-Keyword
search.
"Table of Contents" - a 3rd optional HTML view.
In addition, direct HTML access to individual record level descriptions in their hierarchical context is available via a 4th XSLT stylesheet which also facilitates browsing up and down the hierarchy.
Such access enables the A2A data to be searched and referenced by other online applications, for example by The National Archives' Global Search facility.
It also enables the creation of persistent URLs for individual record level descriptions sub-catalogue.
A permanent HTML cache is also produced (off-line) and made available on-line for partner repositories to link to directly (ie. 100,000 permanent HTML "Full Catalogue" views).
Catalogues, whether retro-converted from paper or from born-digital sources, are collated, processed, standardized to ISAD(G), quality assured, validated and held centrally (at The National Archives) as 100,000 XML files (EAD 1.0)
The depth and detail of each individual catalogue varies enormously:
From 1.5 kb per
XML file up to 1.5 MB per XML file (3.3 GB of XML data in total).
From 1 level only per
file (a fonds) up to 10 nested levels (fonds through item).