Digital Preservation addresses a significant threat to our cultural and economic foundation: the loss of access to valuable and, sometimes, unique information that is captured in digital form through obsolescence, deterioration or loss of information of how to access the contents. Digital Preservation has been defined as “The series of managed activities necessary to ensure continued access to digital materials for as long as necessary” (Jones, Beagrie, 2001/2008). This thesis develops a conceptual model of the core concepts and constraints that appear in digital preservation - DePICT (Digital PreservatIon ConceptualisaTion). This includes a conceptual model of the digital preservation domain, a top-level vocabulary for the concepts in the model, an in-depth analysis of the role of digital object properties, characteristics, and the constraints that guide digital preservation processes, and of how properties, characteristics and constraints affect the interaction of digital preservation services. In addition, it presents a machine-interpretable XML representation of this conceptual model to support automated digital preservation tools. Previous preservation models have focused on preserving technical properties of digital files. Such an approach limits the choices of preservation actions and does not fully reflect preservation activities in practice. Organisations consider properties that go beyond technical aspects and that encompass a wide range of factors that influence and guide preservation processes, including organisational, legal, and financial ones. Consequently, it is necessary to be able to handle ‘digital’ objects in a very wide sense, including abstract objects, such as intellectual entities and collections, in addition to the files and sets of files that create renditions of logical objects that are normally considered. In addition, we find that not only the digital objects' properties, but also the properties of the environments in which they exist, guide digital preservation processes. Furthermore, organisations use risk-based analysis for their preservation strategies, policies and preservation planning. They combine information about risks with an understanding of actions that are expected to mitigate the risks. Risk and action specifications can be dependent on properties of the actions, as well as on properties of objects or environments which form the input and output of those actions. The model presented here supports this view explicitly. It links risks with the actions that mitigate them and expresses them in stakeholder specific constraints. Risk, actions and constraints are top-level entities in this model. In addition, digital objects and environments are top-level entities on an equal level. Models that do not have this property limit the choice of preservation actions to ones that transform a file in order to mitigate a risk. Establishing environments as top-level entities enables us to treat risks to objects, environments, or a combination of both. The DePICT model is the first conceptual model in the Digital Preservation domain that supports a comprehensive, whole life-cycle approach for dynamic, interacting preservation processes, rather than taking the customary and more limited view that is concerned with the management of digital objects once they are stored in a long-term repository.

Η ψηφιακή εποχή για πολλά ευρωπαϊκά αρχεία, βιβλιοθήκες και μουσεία δεν αποτελεί πλέον επιλογή, αλλά πραγματικότητα. Η μετατροπή του πολιτισμικού περιεχομένου όλων των ειδών σε bits και bytes ανοίγει νέους ορίζοντες στην προσέγγιση παραδοσιακού και νέου κοινού, προσφέροντας πρόσβαση σε πολιτισμικές πηγές με τρόπους ασύλληπτους δεκαετίες πριν. Επίσης, οι ανάγκες για αποτελεσματική και εύκολη πρόσβαση σε γεωγραφικές πληροφορίες έχουν αυξηθεί θεαματικά τα τελευταία χρόνια λόγω του αυξανόμενου πλήθους εφαρμογών που χρησιμοποιούν χωρικά δεδομένα, της γενικότερης πολιτικής για ελευθερία πρόσβασης σε πληροφορίες, και της τεχνολογικής εξέλιξης που έχει επιβάλλει νέα φιλοσοφία και νέες δυνατότητες στην πρόσβαση και συσχέτιση δεδομένων. Για να εξυπηρετηθούν αποτελεσματικά οι ανάγκες αυτές, απαιτείται μια ευρεία λειτουργικότητα μεταξύ συστημάτων, δεδομένων και διαδικασιών, γνωστή ως διαλειτουργικότητα. Η διαλειτουργικότητα, τουλάχιστον όσον αφορά την πρόσβαση σε πληροφορίες και τη μεταφορά τους, υλοποιείται μέσω της τυποποίησης τόσο της δομής και της σημασίας τους (content, representation, semantics), όσο και της μορφής μεταφοράς (format) μέσα από ένα σύνολο κανόνων που συνιστούν αυτό που ονομάζεται πρότυπο. Η απαίτηση των χρηστών για υιοθέτηση προτύπων εκτιμάται ότι θα είναι έντονη τα επόμενα χρόνια, ενώ η διαμόρφωση και καθιέρωση ενός τυποποιημένου τρόπου ανταλλαγής δεδομένων φαίνεται ότι είναι η μόνη που μπορεί να διαφυλάξει από απώλεια επενδύσεων σε ήδη παραχθέντα δεδομένα αλλά και εξοικονόμηση χιλιάδων ανθρωποωρών, που τώρα αναλίσκονται για τη διαμόρφωση κατά περίπτωση προγραμμάτων - μεταφραστών, για αντιμετώπιση άμεσων αναγκών. Η παρούσα διπλωματική εργασία επικεντρώνεται στα διαφορετικά πρότυπα τυποποίησης της σημασίας της πληροφορίας, των μεταδεδομένων. Συγκεκριμένα στα μεταδεδομένα της πολιτισμικής και γεωγραφικής πληροφορίας. Αναφέρονται λοιπόν τα δημοφιλέστερα πρότυπα μεταδεδομένων πολιτιστικής και γεωγραφικής πληροφορίας, τα χαρακτηριστικά και η δομή τους καθώς και πραγματικές εφαρμογές τους. / The digital season for many European archives, libraries and museums is not any more an option, but a reality. Converting the cultural information into bits and bytes opens new horizons in attracting traditional and new audience and permits access to cultural resources in ways inconceivable a few decades before. Also, recently the need for efficient and easy access to geographical information has been increased dramatically due to the increased number of applications which use spatial data, to the need of free access to information and to technological evolution which has imposed a new philosophy and new possibilities to access and association of data. In order to serve efficiently these needs, an interaction among different systems, data and processes is required known as interoperability. The interoperability, as far as access to information and carrying information is concerned, is materialized through standardisation. There are three types of standardisation: of the structure, of the meaning (content, representation, semantics) and of the way the information is carried (format) according to a set of rules which compose what we call standard. It is expected that in the next few years a larger number of users are going to use and adopt standards while at the same time the configuration and establishment of a fixed way of exchanging data is the only one to secure loss of investments of already produced data and to save thousands of man-hours that are now wasted for configuring programs per case for facing urgent needs. The present paper is focussed on the various standards of the meaning of the information. We only concern about cultural and geographical information. It presents the most popular standards of metadata of cultural and geographical information as well as real applications that use them.