Architecture Workgroup

Summary of Guidelines

Ref	Guideline
17.1	All version 2.x standards MUST be produced in Document Type Definition (DTD) format.
17.1.1	All MISMO XML DTD structures SHALL be extensible.
17.1.2	DTDs SHALL be developed to support the business line represented within each individual process area.
17.1.3	Each DTD structure SHALL consist of reusable and sharable elements maintained in a central MISMO development library.
17.1.4	All MISMO XML DTD shall follow the Document Type Definition Specification structure as defined in Version 1.0 by the World Wide Web Consortium (W3C).
17.1.5	DTDs SHALL be constructed using containment to represent relationships as opposed to pointing.
17.2	All version 2.x standards MUST be produced in Zero Delta schema format.
17.2.1	Zero Delta schema MAY contain certain elements at the level just below xs:schema.
17.3	All version 3.x standards MUST be produced in XML schema format only.
17.3.1	All MISMO XML Schema shall follow the XML Schema structure as defined in Version 1.0 by the World Wide Web Consortium (W3C).

Guidelines

Ref	Guideline
17.1	All version 2.x standards MUST be produced in Document Type Definition format. Once the data structure and element names are defined (in a Data Model and Logical Data Dictionary), it is fairly easy to convert this information into a DTD format, XML Schema format or any of the other data definition formats. Currently, MISMO uses the DTD format as the method for describing mortgage industry data. It is an approved industry standard that is widely supported in the XML tools and software available today. The MISMO web site serves as the repository for complete drafts and final approved versions of all DTDs.
17.1.1	All MISMO XML DTD structures shall be extensible LINK FOR EXTENSION MEG.
17.1.2	DTDs shall be developed to support the business line represented within each individual process area. There may be more than one transactional DTD for each individual process area. Also, each DTD shall be structured in a way that is optimal for the individual process area or transaction.
17.1.3	Each DTD structure SHALL consist of reusable and sharable elements maintained in a central MISMO development library. It is highly desirable to establish and maintain similar/shared structures within a major process area. It is also desirable to establish and maintain similar/shared structures across multiple major process areas but is not mandatory.
17.1.4	All MISMO XML DTD structure shall follow the Document Type Definition Specification as defined in Version 1.0 by the World Wide Web Consortium (W3C).
17.1.5	DTDs SHALL be constructed using containment to represent relationships as opposed to pointing. The containment structure should be used unless the developer identifies a compelling reason for using a pointing relationship. Compelling reasons for using point relationships include but are not limited to: Use of containment eliminates significant data redundancy. Containment would result in considerable processing in a back end process to reconcile data or building data in a front-end process. Multiple one-to-many and/or many-to-many relationships exist that cannot be represented by a containment hierarchy.
17.2	All version 2.x standards MUST be produced in Zero Delta schema format. At the January 2005 Trimester meeting, MISMO Architecture resolved to require the publication of each Version 2.x transaction going forward with a DTD and a W3C Schema. The Schema is called the “Zero Delta” schema because it must define exactly the same set of document constraints that are defined in the DTD. When these guidelines define a constraint that can not be enforced by a DTD but can be enforced by a W3C Schema it is acceptable to include the constraint in the Schema. For example one can not define a data type in a DTD. These guidelines, however define that a date must be in ISO 8601 format. A DTD declaration of a data will accept any string or any length regardless of formatting. _BirthDate CDATA #IMPLIED All of these XML examples would be acceptable to the DTD definition. _BirthDate=“1945-06-05” _BirthDate=“6/5/1945” _BirthDate=“D-Day” If however, one constrains the XML instance document to obey these guideline only the first example is an ISO 8601 date. Applying the constraint defined in W3C schema as <xs:attribute name=“BirthDate” type=”xs:date“/> Then only the first example is acceptable. The Zero Delta schema uses xs:date to enforce the guidelines.
17.2.1	Zero Delta schema MAY contain certain elements at the level just below xs:schema. The W3C XML Schema Specification allows only certain elements to be at the level just below the xs:schema element. When Present that will appear in the XSD in this order • xs:annotation • xs:include • xs:import • xs:redefine • xs:notation (Optional) • xs:element defining the root element • xs:element for other elements in Latin-1 collating sequence order • xs:complexType • xs:attributeGroup (Optional) • xs:attribute (optional global attributes) • xs:group (Optional) • xs:simpleType This order applies to every schema file, including those containing schema fragments to be used as the source for an xs:import or xs:include. Example 1 - From Credit Request 2.3.1 1 <?xml version=”1.0“ encoding=”iso-8859-1“?> 2 <!–Generated on 7/14/2005 11:38:46 AM from file .\CreditRequest_v2_3_1.dtd–> 3 <xs:schema elementFormDefault=”unqualified“ attributeFormDefault=”unqualified“ xmlns:xs=”http://www.w3.org/2001/XMLSchema“ xmlns:mismo=”http://mismo.org/schema“ xmlns:dsig=”http://www.w3.org/2000/09/xmldsig#“> 4 <xs:annotation> <xs:documentation>File Name:CreditRequest_v2_3_1.dtd Author: MBA MISMO Creation date : September 29, 2004 Modification Date : November 02, 2004 Comments : Copyright 2004 Mortgage Bankers Association of America, Inc.</xs:documentation> </xs:annotation> 5 <xs:import schemaLocation=”SMART_DOCUMENT_xmldsig_core_schema_V_1_02.xsd“ namespace=”http://www.w3.org/2000/09/xmldsig#“> 6 <xs:annotation> <xs:documentation>Envelope 2.3.1: Add ENTITY statement to include the Signature DTD include the W3C XML Digital Signature DTD</xs:documentation> </xs:annotation> </xs:import> 7 <xs:element name=”REQUEST_GROUP“ type=”CREDIT_REQUEST_GROUP_Type“> </xs:element> Line 1 is the mandatory XML processing Instruction with a mandatory encoding selection Line 2 is a comment generated by the DTD to XSD conversion process. It is not required. Line 3 is the schema definition root element with the attributes Line 4 is an annotation about the schema Line 5 is an import of the signature definition Line 6 Is annotation about the imported file Line 7 is the xs:element defining the root element
17.3	All version 3.x standards MUST be produced in XML schema format only. These schema will go beyond the version 2.x Zero Delta schema and take full advantage of the functionality inherent to schemas (and not DTDs). MISMO will not publish DTDs for version 3.x standards.
17.3.1	All MISMO XML Schema shall follow the XML Schema structure as defined in Version 1.0 by the World Wide Web Consortium (W3C).

Changes Since Last Version
See above

Known Issues
Additional Review Required

Contacts
Name	Organization	Contact Details
<ENTER NAME>	MISMO	<ENTER CONTACT DETAILS>

Metadata
Element	Description
Title	MEG0017 DTD and Zero Delta Schema
Identifier	MEG0017
Subject	DTD and Zero Delta Schema in MISMO Standards.
Description	Use and creation of DTDs and Zero Delta Schema.
Type	MISMO Process
Source
Relation	All MISMO Process Areas & Implementation
Coverage	<ENTER COVERAGE HERE>
Creator	<ENTER CREATOR HERE>
Publisher	MISMO
Contributor	Applies equally well to Version 2.x and 3.x
Rights	Copyright 2008 MISMO. All rights reserved.
Date Created	10/23/2006 11:00:00 PM
Date Modified	10/23/2006 11:48:00 AM
Format	Text
Language	En

References

RFC2119	http://rfc.net/rfc2119.html
W3C Schema Structure	http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/structures.html

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