Beyond this, the header order is specifically defined by the spec as not required. Implementations relying on a specific order are violating [RFC 2616 4.2](http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2)

> The order in which header fields with differing field names are received is not significant. However, it is "good practice" to send general-header fields first, followed by request-header or response- header fields, and ending with the entity-header fields.