The EPC code itself belongs to the first category, since it indicates what was observed.
EPC 编码本身属于第一类，因为它指出观察的目标是什么。
Category layouts do not change over time, so you can safely store category paths permanently in your code.
类别布局并不随时间改变，因此您可以放心地将类别路径永久地存储在您的代码中。
Even though a custom category class can be written, this code uses the default category supplied by the API, which will be effective in most cases.
即使一个自定义类别类能够被编写，但是这个代码仍然使用由 API 所提供的默认类别，它在大多数情况下是有效的。
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