Selecting one or more documents in your library and clicking this icon displays Calibre's primaryconversion window, shown in Figure 2.
选择库内的一个或多个文档并单击这个图标会显示出Calibre的主转换窗口，如图2所示。
2
The primary area for improving the conversion process is usually in identifying items in the table of contents and how links to associated portions of your document should be created.
转换过程待改进的主要地方通常都是如何标识目录内的各项以及如何创建与文档相关的各部分的链接。
3
The primary reason they're left out is that they don't make sense inside a PDF file, which is the most common result of formatting-object conversion.