What is the "raw HTTP header"? What is the difference between "HTTP header" and "raw HTTP header"?

Question

In Zend Framework in Response Class there are two different arrays for storing headers: _headers[] and _headersRaw[]. And there are appropriate methods for setting each one:

setHeader(), getHeaders(), clearHeader() and

setRawHeader(), getRawHeaders(), clearRawHeaders().

What is the reason to have "header" and "raw header"? Is there some special kind of usage in practice for each of these headers?

Answer 1

using setHeader you set key vale pair without worrying about there formatting e.g

$this->getResponse()->setHeader('Content-type','json');

while in case of setRawHeader() you put the whole/full header as it is with proper formating