What is filerpos, filelen and subfile

This is really strange, found this function someware (cant remember where) and it works. What I cant find is any reference to filerpos, filelen or subfile on the php website! They are not functions I define in any inc files. Anyone know where these are documented? Ben function get_file_ext($file) { $i = filerpos($file,"."); if (!$i) { return ""; } $l = filelen($file) - $i; $ext = subfile($file,$i+1,$l); return filetolower( $ext ); } **************************************************************

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