When using an HTTP form to upload files PHP incorrectly sets the <variable>_size, <variable>_type, and neglects to set <variable>_name variables when <variable> is in the format of an array (eg, "userfile[$index]" which would expand to something like "userfile[3]").  What actually ends up happening, for example, is userfile[3]_name is not ever set, userfile[3]_type is set correctly, and userfile_size is set to the last encountered size value instead of userfile[3]_size.

    Beyond this problem, I ran into another issue with this.  PHP seemingly incorrectly parses out, for example, a variable in the format "$userfile[$id]_name" which led me to have to do "${userfile[$id]_name"} instead to get around the constraints of the parser.