Description:
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See this thread: http://groups.google.co.uk/group/phpsoa/t/ef945b62fa82da9

Two problems: 
a) Try to access a list element using an xpath. For example
   $do = $record->logicalPort['portId=24'];
results in
   PHP Fatal error:  main(): internal error (747) - invalid dimension type 6 in <source> on line <nn>

In other words, you are using a String (type==6) as an index into a list, but only Integers are valid.  This message is not  intelligible to users.

b) Try to unset a list element using an xpath from the container. For example

  unset($record["logicalPort[portId=24]"]) 

There's no error message. But nothing happens. This expression cannot work, because you cannot use an xpath as a list index, so there should be an error message.