Debugging log mask for NMLSHR. The bit mask is set up at NML initialisation
by translating the logical name NML$LOG. The resulting ASCII hex number
is converted to binary to provide the appropriate mask bit settings.

The values for NML$LOG are defined as follows:

       Bit	Meaning
	0	NICE message network I/O
	1	Permanent data base file I/O
	2	NPARSE state transitions
	3	Test (node loopback) message network I/O
	4	Volatile data base I/O (NETACP QIOs)
	5	MOP direct line I/O
	6	Trace service operation
	7	Raw event data
	<8:15>	Not used
	16	Dump node permanent data base file at initialisation
	17	Dump line permanent data base file at initialisation
	18	Dump logging permanent data base file at initialisation
	19	Dump object permanent data base file at initialisation
	<20:31>	Not used

eg.	$ Assign 00000010 NML$LOG		! <4> set
	$ NCP SHOW KNOW NODES			! Log I/O to volatile database