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Purpose of the XML-Based Site Metadata
Recording, disseminating, and using accurate and timely site information
("metadata") has been a perennial problem in the geodetic community.
SOPAC has developed an XML Schema for geodetic site metadata (e.g., "IGS
Site Logs") to facilitate and improve the documentation of site
information and its exchange among users and applications. It is our
intention that this modern approach will be considered and adopted by
the community after a period of examination and possible revision.
XML-Encoded site logs have many advantages over human-readable log file
formats:
1) XML is a standardized format that is widely used for IT applications.
It is intended to eliminate the problems that are sometimes encountered
when groups/organizations exchange data but use different delimiters or
formats.
2) It is very easy to make changes in XML documents.
3) There are many existing software tools already available to
manipulate XML files, eliminating the need for developing specialized
software.
4) The use of an XML Schema allows for robust data validation.
The XML Schema developed by SOPAC is constructed from multiple smaller
schemas each containing an essential component of site information. The
smaller schemas can be exchanged among users to create documents in a
variety of formats (e.g., IGS Site Logs). XSLT (eXtensible Stylesheet
Language Transformations) is a standardized language developed by
multiple vendors, which can be used to transform XML documents into any
text-based format (e.g., html, pdf, ps, EXCEL). XSLT provides an easy
way to convert XML documents that conform to one schema into XML
documents that conform to other schemas, making information much easier
to pass back and forth between different operating systems. XPATH (XML
Path Language) is a specialized language for addressing specific parts
of an XML document. Tools can be created using XSLT and XPATH that
allow a user to select and display specific information from an XML
document.
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