Ifc发展历史与版本介绍
IFC4.2 (4.2.0.0)
The main purpose of IFC4.2 is to extend the IFC schema to include the description of bridge constructions. Extensions made to the IFC4.1 schema include:
- The spatial structure was extended by IfcFacility and IfcFacilityPart as a basis to describe the spatial breakdown structure of infrastructure facilities.
- IfcBridge and IfcBridge part were added to represent bridges and bridge parts.
- Bridge elements have been integrated into a number of predefined types of building elements.
- IfcBearing, IfcDeepFoundation, IfcVibrationDamper and IfcTendonConduit were added to represent the respective bridge elements.
- IfcRelPositions was added to better support positioning along the alignment.
译：
以IfcFacility和IfcFacilityPart为基础，对空间结构进行了扩展，描述了基础设施的空间分解结构。
增加了IfcBridge和IfcBridge part来表示桥梁和桥梁部分。
桥梁元素已集成到许多预定义类型的建筑元素中。
添加了ifc轴承、IfcDeepFoundation、IfcVibrationDamper和IfcTendonConduit来表示相应的桥梁构件。
增加了IfcRelPositions以更好地支持沿路线的定位。
IFC4.1 (4.1.0.0)
The main purpose of IFC4.1 is to provide a basis for the various infrastructure domain extensions currently being developed (e.g. Rail, Road, Tunnel, Ports & Waterways). Extensions made to the IFC4 schema include:
- Description of alignment as a combination of horizontal and vertical alignment
- Linear Placement according to ISO 19148
- IfcSectionedSolidHorizontal as a new geometry representation particular useful for describing infrastructure facilities
IFC4.1的主要目的是为目前正在开发的各种基础设施领域扩展（例如铁路、公路、隧道、港口和水道）提供基础。对IFC4模式的扩展包括：
将线形描述为水平和垂直线形的组合
符合ISO 19148的线性放置
IfcSectionedSolidHorizontal作为一种新的几何表示形式，特别适用于描述基础设施
IFC4添加2 TC1（4.0.2.1）
IFC4增编2技术勘误1的主要目的
IFC4 Add2 TC1 (4.0.2.1)
The main purpose of IFC4 Addendum 2 Technical Corrigendum 1 is to provide corrections and clarifications to the documentation of the schema and its constituent parts.
IFC4增编2技术勘误1的主要目的是对方案及其组成部分的文件进行更正和说明。
IFC4 Add2 (4.0.2.0)
The main purposes of the IFC4 Addendum 2 are the improvement of the IFC4 Add 1 specification documentation and the necessary enhancements of the schema and property sets that resulted from the ongoing pilot implementations of the first two Model View Definitions, the Reference View and the Design Transfer View. The main change related to improvements to the tessellated geometry for the Reference View, and the advanced boundary representation geometry for the Design Transfer View. All changes made are downward compatible.
Two additional schema enhancements have been added after intensive discussions and considerations:
new subtype of tessellated geometry enabling planar and polygonal boundaries with inner loops
new elementary surfaces and intersection curves for more stable definitions of advanced b-rep's (NURBS)
The documentation format has been further improved for readability. More interlinked definitions, now including property and quantity sets, ifcXML files for all examples, in addition to IFC files, etc.;
The use of concept templates (chapter 4) improved, updated to Version 1.1 of the mvdXML specification and including the snippet of the mvdXML for each template;
The use of concepts at relevant IFC Entities, including the snippets of the mvdXML specification for each concept root, optimized for documentation of the requested functionalities;
NOTE This part is currently still experimental and focuses on documentation of concepts, it requires further improvements before being used for automatic IFC file validation purposes;
A Change Log is provided in the HTML documentation
IFC4附录2的主要目的是改进IFC4 Add 1规范文档，并对前两个模型视图定义（参考视图和设计转换视图）正在进行的试验性实现所产生的模式和属性集进行必要的增强。主要更改与对参考视图的镶嵌几何图形和设计传递视图的高级边界表示几何图形的改进有关。所做的所有更改都是向下兼容的。
经过深入的讨论和考虑之后，又增加了两个架构增强：
支持具有内部循环的平面和多边形边界的细分几何体的新子类型
新的基本曲面和相交曲线，用于更稳定地定义高级b-rep（NURBS）
文件格式已进一步改进，以提高可读性。更多相互关联的定义，现在包括特性和数量集、所有示例的ifcXML文件，以及IFC文件等。；
改进了概念模板的使用（第4章），更新到mvdXML规范的1.1版，并为每个模板包含了mvdXML的片段；
在相关IFC实体中使用概念，包括每个概念根的mvdXML规范片段，针对所请求功能的文档进行了优化；
注：本部分目前仍处于实验阶段，主要集中在概念的文档化，在用于自动IFC文件验证之前需要进一步改进；
HTML文档中提供了更改日志
IFC4 Add1 (4.0.1.0)
A minor update for IFC4 has been published taking into account the experiences and feedback from the pilot implementations and the first Model View definitions. Since 10.07.2015 the IFC4 Addendum 1 is a buildingSMART Final Standard and superseeds the IFC4 Final release.
The main purposes of the IFC4 Addendum 1 are the improvement of the specification documentation and the necessary enhancements of the schema that resulted from the pilot implementations and the first Model View definitions. All changes made are downward compatible.
The documentation format has been further improved for readability. A language independent section to describe the entities and types with their attributes and relationships is now available and separate to the EXPRESS and XSD code;
The use of concept templates (chapter 4) and concepts is greatly enhanced, based on the mvdXML specification to enable better MVD developments and validation;
Minor schema enhancements reflect the experience from pilot implementations of the IFC4 enhancements;
One additional schema enhancement has been added after intensive discussions and considerations, a simplified and far more compact definition of poly lines with arc segments
See the following »summary« of the rationale behind adding this additional geometry definition
A Change Log is provided in the HTML documentation
IFC4的一个小的更新已经发布，考虑到了试验性实现和第一个模型视图定义的经验和反馈。自2015年7月10日起，IFC4附录1是buildingSMART最终标准，取代了IFC4最终版本。
IFC4附录1的主要目的是改进规范文档，并对试验性实现和第一个模型视图定义所产生的模式进行必要的增强。所做的所有更改都是向下兼容的。
文件格式已进一步改进，以提高可读性。现在有一个独立于语言的部分来描述实体和类型及其属性和关系，并且独立于EXPRESS和XSD代码；
在mvdXML规范的基础上，概念模板（第4章）和概念的使用得到了极大的增强，以实现更好的MVD开发和验证；
较小的模式增强反映了IFC4增强的试点实现的经验；
经过深入的讨论和考虑之后，添加了一个额外的模式增强，即具有圆弧段的多边形的简化和更紧凑的定义
请参阅以下“概述”，了解添加此附加几何定义的基本原理
HTML文档中提供了更改日志
IFC4 (4.0.0.0)
Improvements made to the IFC schema include:
Full ISO standard (not a PAS)
Enhanced capability of the IFC specification in its main architectural, building service and structural elements with new geometric, parametric and other features
Enabled numerous new BIM workflows – including 4D and 5D model exchanges, manufacturer, product libraries, BIM to GIS interoperability, enhanced thermal simulations and sustainability assessments
Linking all IFC property definitions to the buildingSMART data dictionary
Improving readability and ease of access to the documentation with numerous implementation concepts and fully linked examples
Containment of ifcXML4 schema, fully integrated into the IFC specification in addition to the EXPRESS schema
Full integration with new mvdXML technology and allows easy definition of data validation services for IFC4 data submissions
Correction of technical problems found since the release of the IFC2x3
Enabling the extension of IFC to infrastructure and other parts of the built environment
Multilingual translations of the schema
对IFC模式的改进包括：
完全ISO标准（非PAS）
以及增强了IFC的建筑几何特征和其他结构要素的性能
实现了众多新的BIM工作流，包括4D和5D模型交换、制造商、产品库、BIM到GIS的互操作性、增强的热模拟和可持续性评估
将所有IFC特性定义链接到buildingSMART数据字典
通过大量的实现概念和完全链接的示例提高文档的可读性和易访问性
包含ifcXML4模式，除了EXPRESS模式之外，还完全集成到IFC规范中
与新的mvdXML技术完全集成，允许为IFC4数据提交轻松定义数据验证服务
IFC2x3发布以来发现的技术问题的纠正
使IFC能够扩展到基础设施和构建环境的其他部分
模式的多语言翻译
IFC2x3 TC1 (2.3.0.1)
Since July 2007 the IFC2x release (as all previous releases of IFC) was superseded by the IFC2x3 Technical Corrigendum 1 - it is strongly recommended to download and use IFC2x3 Technical Corrigendum 1 from now on.
The purpose of this technical corrigendum was to correct several known minor technical problems found since the release of the IFC2x Edition 3 specification and to improve the documentation generally.
Technical corrections include the deletion, modification, or addition of a number of where rules in the EXPRESS schema. As well, a number of functions in the EXPRESS schema have been modified and a new one added. Several derived attributes have been removed from the EXPRESS schema because of ambiguity that could not be resolved satisfactorily.
The modification of the defined type IfcCompoundPlaneAngleMeasure to allow optionally for the expression of angles to a fraction of a second is the only change of the EXPRESS schema that is reflected in the exchange file. This change therefore affects the specification (and existing software implementations) minimally but is an important first step in bringing the IFC and geospatial information specifications into alignment.
Clarifications were introduced to the accompanying documentation in a number of places. All these changes were made to realize the intent of the specification developers and to remove difficulties that implementers were having with data creation and validation. The IFC2x3 to IFC2x3 TC1 change log should be consulted for more details.
自2007年7月以来，IFC2x版本（与IFC的所有先前版本一样）被IFC2x3技术勘误1取代-强烈建议从现在起下载并使用IFC2x3技术勘误1。
本技术勘误表的目的是纠正自IFC2x第3版规范发布以来发现的几个已知的次要技术问题，并全面改进文档。
技术修正包括删除、修改或添加EXPRESS模式中的许多where规则。此外，EXPRESS模式中的许多函数已经修改并添加了一个新函数。由于无法令人满意地解决歧义，一些派生属性已从EXPRESS模式中删除。
将定义的类型ifccompondPlaneAngleMeasure修改为允许将角度表达式更改为几秒钟，这是交换文件中反映的EXPRESS模式的唯一更改。因此，此更改对规范（和现有软件实现）的影响最小，但却是使IFC和地理空间信息规范协调一致的重要的第一步。
在一些地方对随附文件进行了澄清。所有这些更改都是为了实现规范开发人员的意图，并消除实现者在数据创建和验证方面遇到的困难。更多详情，请查阅IFC2x3至IFC2x3 TC1变更日志。
IFC2x3 (2.3.0.0)
The IFC2x3 release was published in Feb 2006 as a successor of IFC2x2 Edition 2. It soon was established as the common ground of IFC implementations, combining previous IFC2x and IFC2x2 implementation threads. IFC2x3 was mainly a quality improvement release not adding scope but refinements on top of IFC2x2.
IFC2x3发布于2006年2月，是IFC2x2第2版的后续版本。它很快被确立为IFC实现的共同点，结合了以前的IFC2x和IFC2x2实现线程。IFC2x3主要是一个质量改进版本，没有增加范围，而是在IFC2x2的基础上进行了改进。
IFC2x2 (2.2.0.0)
The initial IFC2x2 release was published in Mai 2003 as the first successor of the new IFC platform IFC2x. It introduced many extensions to better support the building service and structural domain, e.g. it contains the first IFC sub model for structural analysis, and many extensions for electrical, plumbing and building control definitions. Also the inclusion of 2D content within the model space of a BIM model (line, text, symbols) and presentation information (color, hatching, surface properties, like shading and rendering) are new in IFC2x2.
IFC2x2的初始版本于2003年5月发布，是新IFC平台IFC2x的第一个后续版本。它引入了许多扩展，以更好地支持建筑服务和结构领域，例如，它包含用于结构分析的第一个IFC子模型，以及电气、管道和建筑控制定义的许多扩展。此外，在IFC2x2中，在BIM模型的模型空间中包含2D内容（线条、文本、符号）和表示信息（颜色、图案填充、表面特性，如着色和渲染）也是新的。
IFC2x2 Add1 (2.2.1.0)
Issues with the initial IFC2x2 release were fixed within the IFC2x2 Addendum 1 release, published in July 2004. The required fixes led to an upward compatible schema change. The IFC2x2 Addendum 1 release was recommended for implementation and certification.
初始IFC2x2版本的问题在2004年7月发布的IFC2x2附录1中得到了修复。所需的修复导致了向上兼容的架构更改。建议实施和认证IFC2x2附录1版本。
IFC2x Add1 (2.1.1.0)
Issues with the initial IFC2x release were fixed within the IFC2x Addendum 1 release, published in Nov 2001. The required fixes led to an upward compatible schema change. The IFC2x Addendum 1 release was recommended for implementation and certification.
在2001年11月发布的IFC2x补遗1版本中修复了初始IFC2x版本的问题。所需的修复导致了向上兼容的架构更改。建议实施和认证IFC2x附录1版本。
IFC2x (2.1.0.0)
The initial IFC2x release was published in Nov 2000 as the first IFC platform release. It introduced the concept of a core model and domain extensions. It had been the first IFC release that got a broader implementation base and implementations had been certified using an earlier certification program.
最初的IFC2x版本于2000年11月作为第一个IFC平台发布。它引入了核心模型和域扩展的概念。它是第一个获得更广泛的实现基础的IFC版本，并且已经使用早期的认证程序对实现进行了认证。
