October 31, 2008 NIEM NAMING AND DESIGN RULES VERSION 1.3 URI: http://reference.niem.gov/niem/specification/naming-and-design-rules/1.3/ NIEM NIEM Naming and Design Rules Editors: Webb Roberts, Georgia Tech Research Institute Susan Liebeskind, Georgia Tech Research Institute Mark Kindl, Georgia Tech Research Institute Abstract: This document specifies the data model, XML components, and XML data for use with the National Information Exchange Model (NIEM) version 2.0. Status: This document is a specification for NIEM-conformant XML Schema documents, components, and instances. It represents the design that has evolved from the collaborative work of the NIEM Business Architecture Committee (NBAC) and the NIEM Technical Architecture Committee (NTAC) and their predecessors. This specification is a product of the NIEM Program Management Office (PMO). Send comments on this specification via email to [email protected]. i NIEM NIEM Naming and Design Rules Record of Changes Reference: All, Page, A = Add. No. Date Table, Figure, M = Mod. Revised By Change Description Paragraph D = Del. 1.0 06/08/2007 All A Webb Roberts, Initial version Susan Liebeskind, Internal draft Mark Kindl 1.1 06/27/2007 All M Webb Roberts, Internal draft Susan Liebeskind, Mark Kindl 1.2 08/07/2007 All M Webb Roberts, Public draft Susan Liebeskind, Mark Kindl 1.3 10/31/2008 All M NTAC, Final Webb Roberts, Mark Kindl ii NIEM NIEM Naming and Design Rules Contents 1 Introduction .............................................................................................................................. 1 1.1 Scope ................................................................................................................................ 1 1.2 Audience .......................................................................................................................... 2 1.3 Document Conventions ................................................................................................... 2 1.3.1 Document References ......................................................................................... 2 1.3.2 Normative and Informative Content ................................................................... 2 1.3.3 Formatting ........................................................................................................... 3 1.4 Terminology ..................................................................................................................... 4 1.4.1 RFC 2119 Terminology ........................................................................................ 4 1.4.2 XML Information Set Terminology ...................................................................... 4 1.4.3 XML Schema Terminology ................................................................................... 5 1.4.4 XML Namespace Terminology ............................................................................. 5 1.5 Document Organization ................................................................................................... 5 2 NIEM Conformance ................................................................................................................... 6 2.1 Conformance Targets Overview ...................................................................................... 7 2.2 Reference Schemas .......................................................................................................... 7 2.3 IEPD Subset Schemas ....................................................................................................... 8 2.4 IEPD Extension Schemas and Exchange Schemas ............................................................ 9 2.5 IEPD Constraint Schemas ............................................................................................... 11 2.6 NIEM-Conformant XML Documents and Elements ....................................................... 12 3 The NIEM Conceptual Model .................................................................................................. 13 3.1 NIEM and the RDF Model .............................................................................................. 14 3.2 NIEM Properties ............................................................................................................. 16 3.3 Unique Identification of Data Objects ........................................................................... 17 3.4 NIEM Data Model Is Explicit, Not Implicit ...................................................................... 17 3.5 NIEM Data Model Implementation in XML Schema ...................................................... 17 4 Guiding Principles ................................................................................................................... 19 4.1 Specification Guidelines ................................................................................................. 19 4.1.1 Keep Specification to a Minimum ..................................................................... 19 4.1.2 Focus on Rules for Schemas .............................................................................. 20 4.1.3 Use Specific, Concise Rules ............................................................................... 20 4.2 XML Schema Design Guidelines ..................................................................................... 20 4.2.1 Disallow Content Modification With XML Processors ...................................... 20 4.2.2 Use XML Validating Parsers for Content Validation .......................................... 21 4.2.3 Validate for Conformance to Reference Schemas ............................................ 21 4.2.4 Allow Multiple Schemas for XML Constraints ................................................... 21 4.2.5 Define One Reference Schema Per Namespace ............................................... 22 4.2.6 Disallow Mixed Content .................................................................................... 22 4.2.7 Specify Types for All Constructs ........................................................................ 22 4.2.8 Avoid Wildcards in Reference Schemas ............................................................ 22 4.2.9 Provide Default Reference Schema Locations .................................................. 23 iii NIEM NIEM Naming and Design Rules 4.2.10 Use Open Standards .......................................................................................... 23 4.3 Modeling Design Guidelines .......................................................................................... 23 4.3.1 Namespaces Enhance Reuse ............................................................................. 23 4.3.2 Design NIEM for Extensibility ............................................................................ 24 4.4 Implementation Guidelines ........................................................................................... 24 4.4.1 Avoid Displaying Raw XML Data ........................................................................ 24 4.4.2 Leave Implementation Decisions to Implementers .......................................... 25 4.5 Modeling Guidelines ...................................................................................................... 25 4.5.1 Documentation .................................................................................................. 25 4.5.2 Consistent Naming ............................................................................................ 26 4.5.3 Reflect the Real World ...................................................................................... 26 4.5.4 Be Consistent ..................................................................................................... 26 4.5.5 Reserve Inheritance for Specialization .............................................................. 26 4.5.6 Do Not Duplicate Definitions............................................................................. 27 4.5.7 Keep It Simple .................................................................................................... 27 4.5.8 Be Aware of Scope ............................................................................................ 27 4.5.9 Be Mindful of Namespace Cohesion ................................................................. 28 5 Relation to Standards.............................................................................................................. 28 5.1 XML 1.0 .......................................................................................................................... 28 5.2 XML Namespaces ........................................................................................................... 28 5.3 XML Schema ................................................................................................................... 29 5.4 ISO 11179, Part 4 ........................................................................................................... 29 5.5 ISO 11179, Part 5 ........................................................................................................... 31 6 XML Schema Design Rules ...................................................................................................... 32 6.1 Restrictions on XML Schema Constructs ....................................................................... 32 6.1.1 No Mixed Content ............................................................................................. 33 6.1.2 No Notations ....................................................................................................