6 ms·

ISO-8859-1 (aka. Latin-1) is a superset of ASCII, so all ASCII strings are also valid Latin-1 strings. The section you quoted actually suggests that implementa

ISO-8859-1 (aka. Latin-1) is a superset of ASCII, so all ASCII strings are also valid Latin-1 strings. The section you quoted actually suggests that implementations should support ISO-8859-1 to ensure compatibility with systems that use it.

ko27 3y ago
You should read it again > Newly defined header fields SHOULD limit their field values to US-ASCII octets ASCII octets! That means you SHOULD NOT send Latin1 encoded headers. The opposite of what pzmarzly was saying. I don't disagree Latin-1 being a superset of ASCII or having backward compatibility in mind, but that's not relevant to my response.
- jart 3y ago
  Haven't you heard of Postel's Maxim? Web servers need to be able to receive and decode latin1 into utf-8 regardless of what the RFC recommends people send. The fact that it's going to become rarer over time to have the 8th bit set in headers, means you can write a simpler algorithm than what Lemire did that assumes an ASCII average case. https://github.com/jart/cosmopolitan/blob/755ae64e73ef5ef7d1fe97165705767eda49a3fd/net/http/decodelatin1.c#L33 https://github.com/jart/cosmopolitan/blob/755ae64e73ef5ef7d1... That goes 23 GB/s on my machine using just SSE2 (rather than AVX512). However it goes much slower if the text is full of european diacritics. Lemire's algorithm is better at decoding those.
  - HideousKojima 3y ago
    >Haven't you heard of Postel's Maxim? Otherwise known as "Making other people's incompetence and inability to implement a specification your problem." Just because it's a widely quoted maxim doesn't make it good advice.
- layer8 3y ago
  SHOULD is a recommendation, not a requirement, and it refers only to newly-defined header fields, not existing ones. The text implies that 8-bit characters in existing fields are to be interpreted as ISO-8859-1.
  - verst 3y ago
    There is a RFC (2119) that specifies what SHOULD means in RFCs: > SHOULD This word, or the adjective "RECOMMENDED", mean that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course. https://datatracker.ietf.org/doc/html/rfc2119 https://datatracker.ietf.org/doc/html/rfc2119

ko27 3y ago

You should read it again > Newly defined header fields SHOULD limit their field values to US-ASCII octets ASCII octets! That means you SHOULD NOT send Latin1 encoded headers. The opposite of what pzmarzly was saying. I don't disagree Latin-1 being a superset of ASCII or having backward compatibility in mind, but that's not relevant to my response.

jart 3y ago
Haven't you heard of Postel's Maxim? Web servers need to be able to receive and decode latin1 into utf-8 regardless of what the RFC recommends people send. The fact that it's going to become rarer over time to have the 8th bit set in headers, means you can write a simpler algorithm than what Lemire did that assumes an ASCII average case. https://github.com/jart/cosmopolitan/blob/755ae64e73ef5ef7d1fe97165705767eda49a3fd/net/http/decodelatin1.c#L33 https://github.com/jart/cosmopolitan/blob/755ae64e73ef5ef7d1... That goes 23 GB/s on my machine using just SSE2 (rather than AVX512). However it goes much slower if the text is full of european diacritics. Lemire's algorithm is better at decoding those.
- HideousKojima 3y ago
  >Haven't you heard of Postel's Maxim? Otherwise known as "Making other people's incompetence and inability to implement a specification your problem." Just because it's a widely quoted maxim doesn't make it good advice.
layer8 3y ago
SHOULD is a recommendation, not a requirement, and it refers only to newly-defined header fields, not existing ones. The text implies that 8-bit characters in existing fields are to be interpreted as ISO-8859-1.
- verst 3y ago
  There is a RFC (2119) that specifies what SHOULD means in RFCs: > SHOULD This word, or the adjective "RECOMMENDED", mean that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course. https://datatracker.ietf.org/doc/html/rfc2119 https://datatracker.ietf.org/doc/html/rfc2119