在XML DTD中，属性如何具有两个值？ [英] In XML DTD, how can an attribute have two values?

问题描述

试图实现这样的目标

ATTLIST employee role (leader|analyst|leader,analyst)

我无法将其更改为元素；

where I can't change it into an element; it needs to be an attribute.

似乎DTD在表达式中不喜欢逗号。

It seems like DTD doesn't like commas in its expressions.

推荐答案

XML中的属性不能包含元素。

An attribute in XML cannot contain elements.

您确实反对在任何对象中向属性添加结构办法。如果必须这样做，请保持简单：您可以使用空格或逗号分隔的值表示列表。进行任何进一步的讨论都需要一个与XML解析器不同的单独的微型解析器，仅用于解析属性值。这不是一个好主意，不要期望DTD会提供 NMTOKENS ， IDREFS 提供的支持，或 ENTITIES

You're really going against the grain to try to add structure to attributes in any way. If you must do it, keep it simple: You can represent a list via space or comma-separated values. Going any further runs into requiring a separate micro-parser distinct from an XML parser just to parse the attribute values. It's not a good idea, and don't expect support from DTD beyond that which is provided by NMTOKENS, IDREFS, or ENTITIES

另请参阅： XML元素与XML属性

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