PHP settings

In principle, the PHP variables that affect uploading work in the following way:

• upload_max_filesize: limits the combined size of all files in an upload
• post_max_size: limits the total size of the POST operation; needs to be larger than upload_max_filesize to allow for input variables other than the file(s) and headers.
• memory_limit: apparently needs to exceed post_max_size.

However, it seems that post_max_size cannot be overridden in .htaccess files. Presumably the reason is that it is set at the php.ini value when Apache starts but there's no documentation stating that.