Are MIME headers case sensitive >

Question

I have a small question, does the MIME headers have to be case sensitive ?

for example Content-Type in the RFC 2045 (https://www.ietf.org/rfc/rfc2045.txt) its enclosed in double quotes.so does content type header in the multipart request body has to be case sensitive ?

5.1. Syntax of the Content-Type Header Field

In the Augmented BNF notation of RFC 822, a Content-Type header field value is defined as follows:

 content := "Content-Type" ":" type "/" subtype
            *(";" parameter)
            ; Matching of media type and subtype
            ; is ALWAYS case-insensitive.