endofheader

End of header is a concept used in many text-based data formats and network protocols to denote the boundary between metadata and the main content. The header typically contains key-value pairs that describe the data, such as type, length, encoding, or routing information, while the body carries the actual payload. In some contexts, a literal marker such as endofheader or EndOfHeader may be used as a sentinel to signal the end of the header block, but this is not universal and most common formats rely on a structural delimiter.

In HTTP and email, the end of the header is indicated by a blank line. Each header line follows the form Field-Name: value, and lines can be continued by folding with leading whitespace. After the blank line, the body begins and is interpreted according to the headers, for example via Content-Type and Content-Length. If a content length is not specified, the body length may be determined by the connection closure or by transfer encoding rules.

In MIME and related formats, the header block precedes the body or the multipart sections, and an empty line separates headers from the body. For multipart data, boundaries defined in the headers delineate individual parts, each with its own header set.

For parsers, the typical approach is to read lines until an empty line is found, then treat everything after as the body. Some implementations may also recognize explicit end-of-headers tokens in nonstandard or streaming contexts.

Understanding the end of header is essential for correctly parsing and processing messages, files, and streams across many protocols and applications.