File with Zend at the top?

When I open my client’s checkout page (with a .php extension) in my editor, all I see is the word “Zend” and lots of unrecognizable characters. The beginning of what I see is:

Zend�?2004072203�?3�?36673�?175309�xù Ÿ2?̽MŒfÇq øT]”i¶† ?.O?Q°ÐÖŒ ¦^þg ð?d«e·‡ÿÝ’èÅ�5ÕU_³Ë¬®j~_?Ù=§??0?&?<ì�Ë¡?ú±½ 0Z]?›X?h?Á?Â&#65533;#ê@‘ ?À? H Ä?÷´?™ùòåÿ{Õ¶Ö+tSä?‘ù"##"####AëŸZíî=·µqþúêpqeååÜâÞÁ%S=BJû#à?ì?]¹rýþ*å ÊÍRºymoµ©ÈæöÁþ¥;8S?!a,?ﶖË*ë›ÚïÚ\\\\Û]?®NžÆX1Æz¬ÀSÞ>8Ú?<‰??=çDw 2=’u´\\.öáÿW‡?W?Ë“ˆR&¨@ÚÃ&#65533;? âÎîêêžþì•ÕÓwH!ô?” fxš'?r¸Øߺ²ØùÒiDz‰0Qê· ÕfgeíÀIĨÂ=b°O’Ýîþ¦aÆFŠFˆ^¼§¾äxñÜb¹{éú¦Öš“?Q®g”)6Ù˜ÚÆ«Ã*íg6õ´Ÿ<-¤"„IÍ9˜“厛?¦yo?Á?ܺ¶¹³¸´¥Ý?øw˜ ;$Q’?=¥? [´+[‡Û

My preliminary research into Zend Studio and Zend Server told me nothing. What kind of file is this? What do I need to view the code?

Thanks in advance.

That makes my job a lot harder. Thanks for your help.

You can run it, can’ view source code. There is some decoders for zend encrypted code, it is illegal to do so.

Thanks. So I can run it, but I can’t view it? Is there any way to decompile it so I can see what it’s doing?

This is Zend Gard encrypted file. That need Zend Optimizer to run. This is done by programmers to avoid others seeing the actual php code.