格式要素工作草案

格式意见书(修订)

的格式资源的格式(DC.Format)是指该资源实例化的介质、数据格式和材料，如果需要，还包括其大小。这在资源发现中很重要，因为它允许用户根据显示、操作或以其他方式使用资源可能需要的软件、硬件和其他基础设施进行区分。为了互操作性，应该从枚举列表中选择数据格式或媒体的值，如下所述。DC的值。格式selected from these lists will be used without annotation in simple Dublin Core™.

为电子资源时，建议设置为“DC”。格式可以从列表中选择互联网媒体类型(MIME值)。参考名单保存在http://www.isi.edu/in-notes/iana/assignments/media-types/media-types。请注意，此列表是一个注册表，并且有一个定义良好的过程，用于在适当的情况下添加新类型。

数字资源的大小通常以字节为单位，但对于特定资源可能需要额外的测量，例如，声音的持续时间(以秒为单位)，图像的线性或面维(以像素为单位)，文本的字数。

为其他资源时，建议设置为“DC”。格式be selected from lists of physical media types, such as provided in the艺术和建筑辞典(AAT)，由Getty信息研究所维护(特别是，参见材料方面)。

测量物理物体尺寸的方法有很多，包括线性尺寸、面积、体积和质量。用户应该小心指定这些属性，以便在资源发现中获得最佳性能。

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笔记

IMT方案，推荐用于直流元件DC。格式uses some terms with the same names as occur in the list of values for DC.Type (eg image and text). However, there is an important distinction between DC.Type - which defines the genre of the item which is primarily related to the meaning or content of the resource, and DC.Format - which indicates details of the particular instantiation, including medium and size. This difference is exemplified in the case of text resources stored in image formats; thus, there is no inconsistency with a resource having直流。Type=text and DC。格式=image/g3fax。

直流元件的多个值可以通过几种方式进行管理。一种方法是使用列表作为元素的值。另一种方法是在每个元素中使用单个值重复元素。多个DC值。格式will often occur in the case of media plus size, and for multiple measures of size (eg duration plus bytes for audio, mass plus linear dimensions for physical objects, linear plus pixels plus bytes for images). For these cases there would appear to be no ambiguity using any method. However, there may also be resources for which it is necessary to have multiple media types, for example for compound resources, and in these cases it must be indicated which size information should be associated with which media type. Using some coding methods (eg HTML ) it is not possible to group elements, so the repeated element method would result in ambiguity. It may be preferable to use multiple terms comprising a list in a single value as a grouping mechanism, in order to minimise ambiguity.

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未来的工作

的规范中添加额外的结构显然是可取的格式以便能够自动处理这些值。这将要求属性格式有资格指出格式的类型或方面(例如媒体vs。大小)在一个值中表示，以及正在使用的词汇表或编码模式(例如，将使用从Internet媒体类型列表中选择的值进行限定计划= IMT或者类似的东西)。一种更结构化的DC形式。格式will be particularly important to accommodate the various aspects and measurements of大小，包括多种尺寸测量。可以考虑将单个资源(如质量、体积、长-宽-深等)的大小信息组合在一起的推荐做法，以及用于指示其大小的方法单位用于…大小。

对于具有多个DC值的资源，这是有必要的。键入，以关联每个DC。格式element with the appropriate DC.Type element. The question of methods for grouping DC elements has not been resolved for some coding methods at this time.

结构化的直流。格式will also be used to indicate formats contained in nested-format files (for example, a zip-compressed file will have an outermost format "application/zip" but might contain LaTEX source of format "text/vnd.latex-z").

的结构和语法合格的DC目前还没有解决。精致的结构格式是否会按照一般建议实施合格的直流。