# Solon: A Holistic Approach for Modelling, Managing and Mining Legal Sources
## 2 Architecture
### Data Model  
Various guidelines for good legislative drafting, both at National and E.U. level [10], have established common formats, which most legal documents abide by. In this work the term \"format\"is used as to include topics such as structure, numbering, preferred word use and grammar and template sentences. In a simplified view, a legislative legal document has the following structure:  
* _Introductory part_. The introductory part contains information enabling us to identify the type of document as well as most of its publication and manifestation metadata, e.g., title, number, issuing authority, etc. * _Text body_. The text body is the main part of the document and it may be structured differently depending on the legal document type. It usually follows a well-defined hierarchical layout of text blocks (_legal blocks_), where high level parts of a document, such as the chapter of a law, contain other blocks, such as articles and paragraphs. * _End part_. The end part contains closing formulas, the date, and the signatures. A visual illustration of the aforementioned structure, with manually annotated structural parts and metadata values, for a Greek law is shown in Figure 1.  
Figure 2 shows the basic elements of a legal act, according to the European Union Interinstitutional Style Guide [10], an ongoing effort to standardize formats and to harmonize the presentation of publications. These guidelines, contain uniform stylistic rules and conventions which must be used by all the institutions, bodies, offices and agencies of the European Union. Their application is obligatory for all those involved in document production (paper or electronic), within institutions and bodies of the European Union. Depending on the complexity of the text, elements such as parts, titles, chapters or sections may be used in the preamble, enacting terms and annexes. Figure 1: Overview of the structure of a legal document, with manually annotated structural parts [8]. [PERSON] models legal documents utilizing the LegalDocML schema, a standardisation of Akoma Ntoso (Architecture for Knowledge-Oriented Management of African Normative Texts using Open Standards and Ontology) schema [4]. LegalDocML is an Organization for the Advancement of Structured Information Standards (OASIS) standard XML schema [11], suitable for modelling legislative, parliamentary and judiciary documents. The LegalDocML schema allows the structural and semantic components of legal sources to be accessible by machine-driven processes, thereby providing support for the creation of high-quality legislative information services and improving accountability and efficiency in legislative, parliamentary and judicial contexts. To comply with Greek legal documents i.e., ministerial decisions, laws, regulatory acts of the Council of minister, presidential decrees and administrative acts, we initially analyzed Greek legal sources. Afterwards, we created mapping rules between all the legal blocks (e.g., title, chapters, articles, passages, paragraphs) and their corresponding elements in LegalDocML schema. At the metadata level we also created mapping rules between the LegalDocML schema annotating mechanisms i.e., identification, publication, classification, lifecycle, workflow, temporalData, references and presentation metadata categories and the available/potential metadata types found in Greek legal sources. Finally, for local and proprietary metadata of the platfrom we utilize the _proprietary_ LegalDocML schema metadata format, based on Dublin Core and FOAF properties vocabularies  
Figure 3 provides a visual part of metadata for Greek Law 4172, encoded in the LegalDocML schema, highlighting the usage of the Functional Requirements for Bibliographic Records (FRBR) and Dublin Core vocabularies among others. Figure 2: Basic elements of a legal act, according to European Union Interinstitutional Style Guide [10].