The infamous "implicit *LWS" syntax rule in RFC 2616 allowed whitespace
between chunk-ext parts. Some HTTP agents generate that whitespace. In
my experience, HTTP agents that can parse chunk extensions usually can
handle that whitespace. Moreover, ICAP, which utilizes HTTP/1 chunked
encoding, uses that whitespace when defining the "ieof" chunk extension
in RFC 3507 Section 4.5:
HTTPbis RFCs already allow BWS around "=" for transfer-parameter and
auth-param that have similar syntax. HTTPbis RFCs already allow OWS
around ";" in transfer-extension, accept-ext, t-ranking, media-type, and
other constructs with similar syntax.
For consistency and backward compatibility reasons, RFC 7230 should
allow BWS between chunk-ext parts. IMHO, RFC 7230 should allow OWS
around ";" instead, but I failed to convince the HTTP WG that OWS is
better than BWS there.