HTML 是否区分大小写？
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Is HTML case sensitive?
提问by David Oneill
Is HTML case sensitive?
HTML 是否区分大小写？
In an example I'm working with it says:
在我正在使用的一个例子中，它说：
<!DOCTYPE html>
Would <!doctype html>or <!DocType Html>work differently (or not at all)?
会<!doctype html>或会以<!DocType Html>不同的方式工作（或根本不会）？
回答by Roddick
No, but it's considered good practice to keep HTML markup lowercase.
不，但将 HTML 标记保持为小写被认为是一种很好的做法。
回答by Kenny Dorman
From http://www.w3.org/TR/html5/syntax.html
来自http://www.w3.org/TR/html5/syntax.html
In other words,
<!DOCTYPE html>, case-insensitively.Many strings in the HTML syntax (e.g. the names of elements and their attributes) are case-insensitive, but only for characters in the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL LETTER Z). For convenience, in this section this is just referred to as "case-insensitive".
换句话说，
<!DOCTYPE html>不区分大小写。HTML 语法中的许多字符串（例如元素的名称及其属性）不区分大小写，但仅适用于 U+0041 到 U+005A（拉丁文大写字母 A 到 LATIN CAPITAL LETTER Z）和 U+0061 范围内的字符到 U+007A（拉丁文小写字母 A 到拉丁文小写字母 Z）。为方便起见，在本节中，这仅称为“不区分大小写”。
回答by Liam Newmarch
In addition to the other answers given, if you set the header Content-type: application/xhtml+xml, your browser will throw and XHML error if you don't type DOCTYPE in uppercase and html in lowercase:
除了给出的其他答案之外，如果您设置了 header Content-type: application/xhtml+xml，如果您不输入大写 DOCTYPE 和小写 html ，您的浏览器将抛出 XHML 错误：
<!DOCTYPE html>
Using the XHTML content type isn't recommended because the page won't be rendered in some browsers (e.g. IE8 and below), but it's certainly interesting to know.
不推荐使用 XHTML 内容类型，因为该页面不会在某些浏览器（例如 IE8 及更低版本）中呈现，但了解它当然很有趣。
回答by Russell Dias
HTML is case insensitive. XHTML, that is being XMLis case sensitive.
HTML 不区分大小写。XHTML中，要XML是大小写敏感的。
回答by supercat
Generally, HTML is case-insensitive, but there are a few exceptions. Entity names (the things that follow ampersands) are case-senstive, but many browsers will accept many of them entirely in uppercase or entirely in lowercase; a few must be cased in particular ways. For example, Ç is Ç and ç is ç. Other combinations of upper and lower case are no good.
通常，HTML 不区分大小写，但也有一些例外。实体名称（与符号后面的内容）区分大小写，但许多浏览器会接受其中许多完全大写或完全小写；一些必须以特定方式加以区分。例如，Ç 是 Ç ç 是 ç。其他大小写组合都不好。
回答by Ryan Pedersen
No, you can use any case you want.
不，你可以使用任何你想要的案例。
