XML Parsing

I am posting information to a credit card processing server. This is done over HTTPS (with cURL) and seems to work fine. I get the response that I want from the server, which consists of an XML doc with about 20 tags and their corresponding values. I have gone through the mailing list and manuals, yet I still can't seem to figure out how to get each piece of the XML doc into their own variables. Here is the code I am using: $server = "https://www.creditcard.com"; $path = "xmlhttps/xtrans.asp"; $ch = curl_init(); $requestedurl = "$server" . "/$path"; curl_setopt($ch, CURLOPT_URL, "$requestedurl"); curl_setopt($ch, CURLOPT_POST, 1); curl_setopt($ch, CURLOPT_POSTFIELDS, "$xmlstring"); curl_setopt($ch, CURLOPT_RETURNTRANSFER,0); curl_close ($ch); This replies (as it should) with an XML doc like this: <RESPONSE><SERVICE>CC</SERVICE><SERVICE_TYPE>DEBIT</SERVICE_TYPE><SERVICE_SU BTYPE>AUTH</SERVICE_SUBTYPE><SERVICE_FORMAT>1010</SERVICE_FORMAT><TERMINAL_I D>PC-9999</TERMINAL_ID><PIN>1234</PIN><TRANSACTION_INDICATOR>7</TRANSACTION_ INDICATOR><AMOUNT>5</AMOUNT><ACCOUNT_NUMBER>1234</ACCOUNT_NUMBER><EXPIRATION >1202</EXPIRATION><FIRST_NAME>Michael</FIRST_NAME><LAST_NAME>Conley</LAST_NA ME><ADDRESS>PO BOX 59</ADDRESS><CITY>Auburn</CITY><STATE>CA</STATE><POSTAL_CODE>95604</POSTAL_C ODE><COUNTRY>USA</COUNTRY><PHONE></PHONE><OPERATOR>Somebody</OPERATOR><CURRE NCY_CODE>840</CURRENCY_CODE><TERMINAL_ID></TERMINAL_ID><USER_DATA_0></USER_D ATA_0><USER_DATA_1></USER_DATA_1><USER_DATA_2></USER_DATA_2><USER_DATA_3></U SER_DATA_3><USER_DATA_4></USER_DATA_4><USER_DATA_5></USER_DATA_5><USER_DATA_ 6></USER_DATA_6><USER_DATA_7></USER_DATA_7><USER_DATA_8></USER_DATA_8><USER_ DATA_9></USER_DATA_9><VERBOSE_RESPONSE></VERBOSE_RESPONSE><SERVICE_PROVIDER> 10</SERVICE_PROVIDER><TRANSACTION_ID>03509KQEGVHMGED4</TRANSACTION_ID><LOCAL _TIME>172823</LOCAL_TIME><LOCAL_DATE>04302001</LOCAL_DATE><EXCHANGE_RATE>1</ EXCHANGE_RATE><MRC>00</MRC><ARC>00</ARC><RESPONSE_TEXT>NO MATCH</RESPONSE_TEXT><APPROVAL_CODE>VITAL6</APPROVAL_CODE><AVS_RESPONSE>N</A VS_RESPONSE><COMMERCIAL_RESPONSE>0</COMMERCIAL_RESPONSE></RESPONSE> What I need to do now is get certain parts of the return string. How do I assign the value in the <APPROVAL_CODE> tags to the variable $approvalcode? I also need to get several other parts of the XML string assigned to variables so that I can use them elsewhere. I can't seem to figure out how to do this. I know that I need to change the "CURLOPT_RETURNTRANSFER" to "1" to allow the information to be placed somewhere other than the screen for processing, but after that I am not sure how to do this. I have gone through the mailing lists and through the docs online, but I'm having no luck. Any help is appreciated.