</blockquote>

http://24ways.org/advent/transitional-vs-strict-markup

这篇文章是关于transitional-vs-strict，过渡型和标准型xhtml的区别，里面提到了内容模型的区别，有关于<blockquote>的内容，在strict中，引用的内容必须使用块级元素将其包含，通常是<p>,<div>中。
Content model differences
An element type’s content model describes what may be contained by an instance of the element type. The most important difference in content models between Transitional and Strict is that blockquote, body, and form elements may only contain block level elements. A few examples:
text and images are not allowed immediately inside the body element, and need to be contained in a block level element like p or div
input elements must not be direct descendants of a form element
text in blockquote elements must be wrapped in a block level element like p or div
所以，我认为，在strict型必须用块级元素将引用文字包含，而在非strict型中就不必了，但是建议这样这样做，因为strict型文档更严格，也算是向后兼容了。