Servers and proxies do not have to serve a document in a character encoding that covers the entire document character set. This specification does not mandate which character encodings a user agent must support. Thus, a user-agent receiving a hexadecimal FFFE as the first bytes of a text would know that bytes have to be reversed for the remainder of the text. For information about ISO 8859-8 and the bidirectional algorithm, please consult the section on bidirectionality and character encoding . Some servers examine the first few bytes of the document, or check against a database of known files and encodings.
Many modern servers give Web masters more control over charset configuration than old servers do.
The server should provide this information. META declarations should appear as early as possible in the HEAD element. For cases where neither the HTTP protocol nor the META element provides information about the character encoding of a document, HTML also provides the charset attribute on several elements. By combining these mechanisms, an author can greatly improve the chances that, when the user retrieves a resource, the user agent will recognize the character encoding. The charset attribute set on an element that designates an external resource.