这是因为回退机制只能用于指令元素而不能用于声明。

That is because the fallback mechanism only works for instruction elements, not declarations.

youdao

关于XSLT中的“指令”和“声明”元素请参阅结构表和后面的说明。

See the structure table and the following remarks for details about "instruction" and "declaration" elements in XSLT.

youdao

在两个版本的XSLT中第2层的元素都称为指令。

The elements at level 2 are called instructions in both versions of XSLT.

youdao