m元素表示文本被“加上标志”，但是不一定要强调。

The m element indicates text that is "marked" somehow but not necessarily emphasized.

youdao

正如下标文本一样，可使用XSL - FO vertical - align属性来处理上标文本。

Just as with subscript text, you use the XSL-FO vertical-align property to handle superscript text. Here's an HTML sample.

youdao

很多书写用字母(比如：法语)需要上标或下标才能正确展示。在这些情况下，SUB和SUP元素应该用来标记文本。

Many scripts (e. g., French) require superscripts or subscripts for proper rendering. The sub and sup elements should be used to markup text in these cases.

youdao