start-of-heading signal

例句：

1. 1. This isthe first line of text that appears before a heading.
   这是出现在标题之前的第一行文本。
2. 2.The software uses a start-of-heading signal to indicate the beginning of a new section.
   该软件使用标题开始信号来指示新章节的开始。
3. 3.When designing a document, it's important to use a start-of-heading signal to ensure consistency in formatting.
   在设计文档时，使用标题开始信号以确保格式一致性很重要。