Re: 10.12 Content-Length

> HTTP/1.1 request messages that contain an entity body MUST contain
> either a valid Content-Length field value or a Transfer-Encoding: chunked
> entity header and a chunked entity body.

It would be more general and simpler just to say that 

It must be possible for the recipient to reliably determine the end of
a HTTP/1.1 request method containing an entity body, e.g., because the
request has a valid Content-Length field, uses transfer-encoding:
chunked or a multipart body.

(Note that file upload suggests using multipart/form-data for posting;
this form is self-delimiting and doesn't need either content-length
*or* chunked encodings.)