最近几年来,地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持,如城市管理、区划、环境整治等等,地理信息成为信息时代重要的组成部分之一; “数字地球”概念的提出,更进一步推动了作为其技术支撑的GIS的发展。 与此同时,一些学者致力于相关的理论研究,如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面,并且这两个方面构成了相互促进的发展过程。
The W3C standardized procedure is divided into seven different steps. In the process of publishing a new standard by the W3C, the specification isgradually established as a recommended standard from a simple idea through the following strict procedure: The W3C received a submission A record issued by the W3C Create a working group by W3C A working draft issued by the W3C A candidate recommendation issued by the W3C A proposed recommendation issued by the W3C Recommendations issued by W3C In the following chapters of this tutorial, the corresponding activities of HTML, CSS, XML, and XSL at the W3C are summarized, including the status and timeline of each Web standard. Any W3C member can submit a proposal that wants to be a Web standard to the alliance. Most W3C recommendations originate from a submission to the federation. If an item is submitted in the W3C’s area of work (or charter), then the W3C will decide whether to initiate improvements to the proposal. Typically, a submission to the W3C becomes a record. A record is a description of a proposal refined as a public document. The W3C records only user discussions. The release of the record does not represent its approval. The content of the record is edited by the member who submitted the record, not the W3C. Records can be updated, replaced, or discarded at any time. The release of the record does not indicate that the W3C has initiated any work related to this record. When a submission is recognized by the W3C, a working group is formed, including members and other interested groups. The working group usually defines a schedule and issues draft work on the proposed standards. W3C working drafts are usually posted on the W3C website, along with an invitation to public comments. The draft work will describe the work in progress, but it should not be usedas any reference material. Its contents can be updated, replaced or discarded at any time. Some specifications are more complex than others and may require more funding, more time, and more testing from members and software developers. Sometimes these specifications are released as candidate recommendations. Candidate recommendations are also “work in progress” and should not be used as reference materials. This document can be updated, replaced, or discarded at any time. The proposed recommendation represents the final stage of work in the working group. Recommending a recommendation is also a “work in progress”. This document can be updated, replaced, or discarded at any time. But even if it does not mean any official approval from the W3C, in many cases, the proposed recommendation is close to the final recommendation in terms of content and timing. The W3C recommendation has been reviewed by W3C members and formally approved by the W3C director. The W3C recommendation is a stable document and can be used as reference material. In the following chapters of this tutorial, the corresponding activities of HTML, CSS, XML, and XSL at the W3C are summarized, including the status and timeline of each Web standard. 4.3.1. Approval steps of W3C specification ¶
4.3.2. W3C Submissions ¶
4.3.3. W3C Notes ¶
4.3.4. W3C Working Groups ¶
4.3.5. W3C Working Drafts ¶
4.3.6. W3C Candidate Recommendations ¶
4.3.7. W3C Proposed Recommendations ¶
4.3.8. W3C Recommendations ¶