[mfer]

At the time S3 launched the URL spec was RFC 1738 and we had HTML 4.01[2]. And, the URI syntax (all the way back in 1998) noted to use %20 for a space[3].

As far as I can tell, this traces its history back to encoding for forms[4]. It's been used far beyond the encoding for forms and maybe someone can explain why.

It's also not just PHP whose function is that way. In Python urlencode encodes as a + (at least in 2.7.x).

I remember working on the web many years ago where "+" is what was used. This may have been a spec misinterpretation or something else. In any case, it was common enough.

Note, I'm not saying it was right. Just not uncommon.

[1] https://www.ietf.org/rfc/rfc1738.txt [2] https://www.w3.org/TR/html401/ [3] https://www.ietf.org/rfc/rfc2396.txt [4] https://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.1