INGRES system flags:

D	decomposition trace info
G	GEOQUEL trace info
L	disable map UPPER -> lower case
M	terminal monitor trace info
O	OVQP trace info
P	parser trace info
Q	query modification trace info
T	support routine trace info
Z	DBU trace info
&	EQUEL flag
a	automatic buffer clear on/off
b	batch update on/off
cN	set min "c" width to N
d	dayfile on/off
fWXM.N	set "fW" format to XM.N
iWN	set "iW" format to N
lN	set page length to N + 6 lines (default 60)
rT	set ret into to T, default "isam".  (isam, cisam, hash, chash,
	cheap).
s	prompt character on/off
uXX	set user code to XX

Trace flags 0 -> 19 are used by the control monitor and should
not be otherwise used.  Trace flags 20 -> 29 are used by the
access methods and utility routines and are reserved.  Flags
30 -> whatever are for general use by the process.

Upper case are generally for system debugging, lower case flags are
user flags.