Those characters that do not map will be substituted by a reserved code point.

那些没有映射的字符将通过预留的代码点来代替。

youdao

Every code page has reserved at least one code point for substitution.

每一个代码页至少预留了一个代码点，以便进行替代。

youdao

As only 27 tokens are available for elements -- 5 bits, with the values 0 through 4 being reserved -- complex vocabularies need to be multiplexed by organizing token sets into separate code pages.

由于元素的标记只有27种——共占用5位，其中值从0到4为保留标记——复杂名词则需要进行复合，将标记集组织到不同的代码页中。

youdao

Or does it want to keep the iPhone app market reserved for people who can either code computer apps or afford to hire a developer?

FORBES: Will Apple Respond To Google With "HyperCard For iPhone" App Tool?