标识符的长度没有限制。

Identifiers can be of any length.

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在早期，编程工具受制于标识符的长度，故而注释成为了传达编程涵义的唯一选择。

In early days, your tool often had a limit on identifier character length that could be used so the comments were the only choice for delivering some meaning to other human beings.

youdao

DB 2 Database for Linux, UNIX, and Windows Version 9.5开始支持长达128个字符的长标识符；之前，它只支持长度为18个字符的标识符。

DB2 Database for Linux, UNIX, and Windows Version 9.5 started supporting long identifiers up to 128 characters; previously it supported identifiers only 18 characters in length.

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