User-Friendly Form Validation with PHP and CSS
Subject:   POST requests should not be redirected
Date:   2004-04-29 09:13:48
From:   shiflett
Response to: POST requests should not be redirected

That is how the specification is written, but it is not how it is applied in practice. Basically, 302 is treated exactly like the description of 303. In fact, 303 was added so that the ambiguity could be removed. If 303 was supported as consistently as 302 (e.g., by both old and new agents), we would probably return that instead of 302 when a developer sets a Location header.