Format of NESL Producer Event Control Block (PECB):
Offset	Size	Description	)
 00h	WORD	PECB_MajVer  Major Version of this structure (=1)
 02h	WORD	PECB_MinVer  Minor Version of this structure (=0)
 04h	DWORD	PECB_NextProducer   -> next PECB.  NULL if last.
 08h	DWORD	PECB_ClassName	    -> ASCIZ string identifying event
					  class (see #03025)
 0Ch	DWORD	PECB_ConsumerList   -> list of consumers for this event class
 10h	DWORD	PECB_DataPtr	    -> points to additional data during events
 14h	DWORD	PECB_Flags
		Bit 0	=0  consumers should be called "top down" for this
			    event class.  (OSI level 7 down to OSI level 1)
			=1  consumers should be called "bottom up"
		Bits 1-31   Reserved =0
 18h  8 BYTEs	PECB_Reserved (all zeros)
Note:	Although the event producer provides the memory for the PECB, the
	  NESL module controls this memory until the event class is
	  de-registered.
	While owned by NESL, this structure should be treated as read-only,
	  except for the PECB_DataPtr field.