IMS Question and Test Interoperability XML Binding

Version 2.1 Public Draft (revision 2) Specification

Copyright © 2006 IMS Global Learning Consortium, Inc. All Rights Reserved.
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Document Name: IMS Question and Test Interoperability XML Binding

Date Issued:

8 June 2006

Caution: this specification is incomplete in its current state. The IMS QTI project group is in the process of evolving this specification based on input from market participants. Suppliers of products and services are encouraged to participate by contacting Mark McKell at [email protected]. This specification will be superseded by an updated release based on the input of the project group participants.

Please note that supplier's claims as to implementation of QTI v2.1 and conformance to it HAVE NOT BEEN VALIDATED by IMS GLC. While such suppliers are likely well-intentioned, IMS GLC member organizations have not yet put in place the testing process to validate these claims. IMS GLC currently grants a conformance mark to the Common Cartridge profile of QTI v1.2.1. The authoritative source of products and services that meet this conformance is contained in the IMS online product directory http://www.imsglobal.org/ProductDirectory/directory.cfm

Thank you for your interest in and support of IMS QTI.

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1. Introduction

2. References

3. Binding of Complex Types

4. Binding of Simple Types

4.1. boolean
4.2. coords
4.3. date
4.4. datetime
4.5. duration
4.6. float
4.7. identifier
4.8. integer
4.9. language
4.10. length
4.11. mimeType
4.12. string
4.13. string256
4.14. styleclass
4.15. uri
4.16. valueType

5. Binding Values of Item Variables

5.1. boolean
5.2. directedPair
5.3. duration
5.4. file
5.5. float
5.6. identifier
5.7. integer
5.8. pair
5.9. point
5.10. string
5.11. uri

6. XML Binding Reference

1. Introduction

The information model defines a set of classes and data types in an abstract way. When faced with the real task of communicating data between systems these abstract concepts need to be bound to some physical representation, such as a stream of bytes in a computer file.

This document describes the required method of binding the information model when the physical representation is an XML Document. The binding rules are given primarily in the form of an XML Schema with the following target namespace: http://www.imsglobal.org/xsd/imsqti_v2p1. To assist developers who wish to check the validity of QTI XML documents using tools that support document type definitions (DTDs) the binding rules are also represented as a DTD, however, the DTD is not able to express all the constraints contained in the schema and document instances should validate against the schema. QTI document instances must validate against one of the schema or DTD.

2. References

ISO8601: ISO8601:2000 Data elements and interchange formats – Information interchange – Representation of dates and times; Published: 2000
MathML: Mathematical Markup Language (MathML), Version Version 2.0 (Second Edition); http://www.w3.org/TR/2003/REC-MathML2-20031021/; Published: 2003-10-21
RFC1766: RFC 1766 Tags for the Identification of Languages; H. Alvestrand; http://www.ietf.org/rfc/rfc1766.txt; Published: 1995-03
RFC2045: RFC 2045-2048 Multipurpose Internet Mail Extensions (MIME)
RFC3066: RFC 3066 Tags for the Identification of Languages; H. Alvestrand; http://www.ietf.org/rfc/rfc3066.txt; Published: 2001-01
XHTML: XHTML 1.1: The Extensible HyperText Markup Language

3. Binding of Complex Types

Complex types, those that contain other objects through composition and/or have attributes, are represented in the schema as elements with complex content in a straightforward way. Classes that are used as base classes (typically labeled abstract in the model) are used to define an element group consisting of a single choice listing all the non-abstract classes derived from them. Classes with attributes are used to define attribute groups and those that contain other objects (including through inheritance) are used to define element groups describing them.

Elements defined by [XHTML] are not imported directly from an external schema but are instead re-declared as part of the QTI schema. At the time of writing the use of schema for XHTML is at an experimental stage. However, the math element defined by [MathML] is imported from the MathML schema. Note that the use of the MathML schema excludes the use of the entity declarations for mathematical symbols defined in the original MathML DTD and therefore these should not be used for referring to characters within QTI document instances.

4. Binding of Simple Types

Simple datatypes are bound directly to the closest equivalent type in XML Schema, for example, boolean is bound directly to xsd:boolean. Enumerations are bound as enumerated restrictions of xsd:NMTOKEN.

The information model says nothing about how simple types are to be represented in text. For example, the boolean type is an abstract boolean which can be either logically true or logically false. By binding these simple types using XML Schema they automatically inherit the lexical bindings described there. A lexical binding is just a set of rules for representing the abstract type as a run of text characters. For example, XML Schema allows the following strings to represent the values of xsd:boolean: "true", "false", "1" and "0".

XML DTDs have a smaller vocabulary for defining simple types and is therefore not able to impose the same lexical constraints as the schema. Applications that generate QTI document instances that validate against the DTD must still use the same lexical bindings defined by schema even though these will not be checked automatically by the XML parser. For example, in the DTD the boolean type is bound only to NMTOKEN and therefore the XML parser will permit many more strings than the four listed above. However, strings such as "yes" and "no" are still forbidden.

The following sections spell out the bindings for the simple types defined in the information model. Simple types are defined as datatypes in the information model and are used as the types of attributes (which are bound to attributes in the XML representation) or as the types of simple aggregations (which are bound to elements without attributes in the XML representation). Where the information model indicates multiple occurrences of a simple type these are bound using space separation of individual values in attributes or multiple instances of the element in the case of aggregations.

4.1. boolean

Bound using the XML schema boolean. The legal literals are defined there to be:

true
false
1
0

4.2. coords

The coords datatype is bound as a single string value which is obtained by concatenating a list of length values using comma as the list separator. Note that the use of comma is for compatibility with [XHTML]. Example values:

10,100,50,200
50,60,50%
60,50,110,100,60,150,10,150,60,50
50%,50%,20,25

4.3. date

Bound using the XML schema date type. The legal literals are defined as a subset of [ISO8601]. Note that only extended calendar forms are supported (forms with hyphen field delimiters) and that all components of the date must be specified. The information model value space for the date type does not include time zone information or expanded forms (negative dates and dates beyond 9999) so these are excluded from the binding. Example values:

2006-03-22

4.4. datetime

Bound using the XML schema dateTime type. Expanded forms should not be used. Example values:

2006-03-22T12:33:25TZ
2006-03-022T12:33:25+01:00

4.5. duration

Bound using the XML schema double type. Example values:

3600.0
5400.0
7.2E+02

4.6. float

Bound using the XML schema double type. Note that the range of values accepted by float corresponds to XML schema's double type and not it's float type.

1
3.14
3E+08

4.7. identifier

Identifiers are defined in terms of allowable sequences of characters and are bound in the schema to NCName. Example values:

A
choice4
correct

4.8. integer

Bound using the XML schema int type. Example values:

1
+3
-4

4.9. language

Bound using the XML schema language type. Languages are represented according to the conventions of [RFC1766] which itself has been made obsolete by [RFC3066]. Example values:

en-US
en-GB
en

4.10. length

Length values are represented as non-negative integers, optionally followed by the percent character. There is no corresponding type in XML schema, the binding is through a pattern restriction of the basic string type. Lengths must match the following pattern [0-9]+%?. Example values:

10
50%

4.11. mimeType

Represented as strings conforming to the definition of type "/" subtype in [RFC2045]. Example values:

text/plain
image/gif
application/octet-stream

http://www.example.com/
images/icon.gif
mailto:[email protected]

4.16. valueType

See Binding Values of Item Variables.

5. Binding Values of Item Variables

This specification defines a model for maintaining the values of item variables during a test or item session. Item variables may have single values, or may be containers for multiple values. In each case, the single values are represented using instances of the class value in declarations and reports, the class baseValue when used in expressions and the datatype valueType when given as an attribute value. The following discussion applies to all three contexts.

Each value instance can contain a single value of any of the baseTypes supported by the specification. The content of a <value> element is therefore bound to the general string type in XML schema. However, the element content must satisfy the binding for the associated baseType as described below.

5.1. boolean

As for the simple type boolean.

5.2. directedPair

A space separated list of two identifier values with the source identifier first, followed by the destination identifier. Example values:

A B
choice5 choice1
apple fruit
carrot vegetable

5.3. duration

The number of seconds, expressed as a floating point number and bound according to the rules for the simple type float.

5.4. file

Files are represented using MIME message streams, including the specification of headers for providing information about content type and encoding. For more information see [RFC2045]. Example value:

Content-Type: image/gif; name="works.gif" ; x-mac-type="47494666"
 ; x-mac-creator="4A565752"
Content-Disposition: attachment; filename="works.gif"
Content-Transfer-Encoding: base64
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5.5. float

As for the simple type float.

5.6. identifier

As for the simple type identifier.

5.7. integer

As for the simple type integer.

5.8. pair

A space separated list of two identifier values.

A B
choice5 choice1
apple pear
carrot potato

5.9. point

A space separated list of two integer values, bound in the same way as the XML schema type int. The first value is the horizontal component, the second the vertical.

10 50
32 16

5.10. string

As for the simple type string.

5.11. uri

Title	IMS Question and Test Interoperability XML Binding
Editors	Steve Lay (Cambridge Assessment), Pierre Gorissen (SURF)
Version	Public Draft v2.1 (revision 2)
Version Date	8 June 2006
Status	Public Draft (revision 2) Specification
Summary	This document describes the QTI XML Binding specification.
Revision Information	8 June 2006
Purpose	This document has been approved by the IMS Technical Board and is made available for public review and comment.
Document Location	http://www.imsglobal.org/question/qtiv2p1pd2/imsqti_bindv2p1pd2.html

Name	Organization
Dick Bacon	University of Surrey
Niall Barr	Question Mark
Lance Blackstone	Pearson VUE
Jeanne Ferrante	ETS
Pierre Gorissen	SURF
Regina Hoag	ETS
Gopal Krishnan	Pearson VUE
Steve Lay	Cambridge Assessment
Rowin Young	CETIS

Version No.	Release Date	Comments
Base Document 2.1	14 October 2005	The first version of the QTI v2.1 specification.
Public Draft 2.1	9 January 2006	The Public Draft v2.1 of the QTI specification.
Public Draft 2.1 (revision 2)	8 June 2006	The Public Draft v2.1 (revision 2) of the QTI specification.