核心内容摘要
seo怎么做好_SEO优化实战指南：高效提升排名的核心策略
SEO关键词排名监测及竞争对手分析方法
Despite the name , pragma directives are almost entirely unrelated to HTTP headers. Implementers and web developers are best off thinking of them as entirely separate, and the name as being a historical accident. In more detail, although the keyword has the same processing model as the corresponding `` header, every other standardized pragma directive has at least slightly different behavior than the similarly-named header. (And usually dramatically-different behavior.) Implementers or specification writers contemplating adding new document-level pragmas or HTTP header-controlled switches should be cautious about this mismatch, and avoid perpetuating the existing confusion by adding the same or similar behavior to both an HTTP header and an pragma. Instead, consider providing only an HTTP header, or if an in-document pragma is needed, consider adding a new attribute to similar to the model used by the attribute. (Note that avoiding in-document pragmas is often the better choice, since the DOM is mutable. Thus, even in the simple case where the developer does not add, remove, or mutate elements, the policy will go from un-applied to applied during parsing, which can have complex implications.)
