format

sf-binary - structured fields byte sequence as defined in RFC8941

Base type: string.

The sf-binary format represents a structured fields byte sequence as defined in RFC8941.

sf-binary = ":" *(base64) ":"
base64    = ALPHA / DIGIT / "+" / "/" / "="

A Byte Sequence is delimited with colons and encoded using base64 (RFC4648, Section 4).

This format is appropriate for a header value that must conform to the sf-binary structured field definition.