Metalanguage XML and the type of element scheme

DURING THE LAST DECADES A TOOL FOR ELECTRONIC PROCESSING KNOWN AS MARK UP LANGUAGES HAS BEEN AND IS STILL BEING DEVELOPED. FROM THE MARC FORMAT OF THE 60'S TO THE XML. ESTABLESHED IN OUR DAYS, A VERY CLEAR EVOLUTION HAS, NO DOUBT, TAKEN PLACE. THIS PAPAER ENTEDS TO SETTLE THE ISSUE OF THE HISTORIAL AND FUCTIONAL EVOLITION OF THE MARKS-UP LANGUGES AND OF THEIR CHARACTERISTICS, ADVANTAGES, LIMITATIONS AND EXPECTATIONS. WITHIN THE SPECIFICATIONS OF XML, A PARTICULAR TECHNIQUE FOR THE DECLARATION AND HANDLING OF DOCUMENTARY INFORMATION HAS BEEN DEVELOPED RECENTLY. THE TECHNIQUEIS KNOWN AS TYPE OF ELEMENT SCHEME, OR SIMPLY SCHEMES, BUTIS GOES WELL BEYONG THE SIMPLE AND VERY WELL KNOWN DEFINITION OF DOCUMENT THROUGH A DESCRIPTOR OF TYPE OF DOCUMENT (DTD). THE SCHEMES OFFER A MUCH WIDER POSSIBILITY FOR DEFINING CLASSES OF DOCUMENTS. THIS PAPER ATTEMPTS TO ESTABLISH THESE POSSIBILITIES IN ORDER TO UNDERSTAND THE POTENTIALITY OF SCHEMES, ITS STATE OF ART, ITS TENDENCIES AND ALSO THE IMPORTANCE THAT THE DEVELOPMENT OF SPECIAL SCHEMES MAY HAVE FOR CERTAIN CLASSES OF DOCUMENTS IN OUR MEXICAN LIBRARY ENVIRONMENT FOR A BETTER IMPLEMENTATION AND EXPLOITATION OF DIGITAL COLLECTIONS.