Unless otherwise indicated, the description of each MASK shows what this bit means if it's set.
80EC0 | 
 SysNib1
 | 
ISysFlags 1
 | 
001C0 | 
 NoRolDA2MASK
 | 
DA2 can't be rolled up to become 
valid <see>SysNib1
 | 
002C0 | 
 AbbrStkMASK
 | 
Display obj types only 
<see>SysNib1
 | 
004C0 | 
 DA2bIsEdMASK
 | 
DA2b shows the edit line 
<see>SysNib1
 | 
008C0 | 
 IgnorAlmMASK
 | 
Ignore <see>ALARMSDUE in <see>GETKEY 
<see>SysNib1
 | 
80EC1 | 
 SysNib2
 | 
ISysFlags 2
 | 
001C1 | 
 ReqClkOnMASK
 | 
Flag for System Request of CLKON 
state <see>SysNib2
 | 
002C1 | 
 ServModeMASK
 | 
Server mode on <see>SysNib2
 | 
004C1 | 
 TrackMASK
 | 
New context needs to be compared 
with old <see>SysNib2
 | 
008C1 | 
 BadMenuMASK
 | 
Menu system corrupt <see>SysNib2
 | 
80EC2 | 
 SysNib3
 | 
ISysFlags 3
 | 
001C2 | 
 UNDOMASK
 | 
Automatic stack save <see>SysNib3
 | 
002C2 | 
 INSERTMASK
 | 
Insert/replace mode <see>SysNib3
 | 
004C2 | 
 ALGMASK
 | 
Algebraic entry mode <see>SysNib3
 | 
008C2 | 
 PRINTINGMASK
 | 
<see>SysNib3
 | 
80EC3 | 
 SysNib4
 | 
ISysFlags 4
 | 
001C3 | 
 DA2aTempMASK
 | 
DA2a temporarily valid <see>SysNib4
 | 
002C3 | 
 DA2bTempMASK
 | 
DA2b temporarily valid <see>SysNib4
 | 
004C3 | 
 DA3TempMASK
 | 
DA3 temporarily valid <see>SysNib4
 | 
008C3 | 
 RebuildMASK
 | 
Menu requires TOUCHTAB rebuild 
each time it is redisplayed 
<see>SysNib4
 | 
80EC4 | 
 SysNib5
 | 
ISysFlags 5
 | 
001C4 | 
 COMMANDMASK
 | 
CMD history enabled <see>SysNib5
 | 
002C4 | 
 BLINKMASK
 | 
Active Timer1 Int's <see>SysNib5
 | 
004C4 | 
 LOWERMASK
 | 
Lowercase keys <see>SysNib5
 | 
008C4 | 
 STKDCMASK
 | 
Decompilation for stack display 
(not editing) <see>SysNib5
 | 
80EC5 | 
 SysNib6
 | 
ISysFlags 6
 | 
001C5 | 
 Do1UserMASK
 | 
One-key user mode <see>SysNib6
 | 
002C5 | 
 ASuspOKMASK
 | 
Suspending current environment 
is allowed <see>SysNib6
 | 
004C5 | 
 BadPOLUIMASK
 | 
POL UI possibly corrupt <see>SysNib6
 | 
008C5 | 
 DA1TempMASK
 | 
DA1 temporarily valid <see>SysNib6
 | 
80EC6 | 
 SysNib7
 | 
ISysFlags 7
 | 
001C6 | 
 DA1ValidMASK
 | 
DA1 known to be valid <see>SysNib7
 | 
002C6 | 
 DA2aValdMASK
 | 
DA2a known to be valid <see>SysNib7
 | 
004C6 | 
 DA2bValdMASK
 | 
DA2b known to be valid <see>SysNib7
 | 
008C6 | 
 DA3ValidMASK
 | 
DA3 known to be valid <see>SysNib7
 | 
80EC7 | 
 SysNib8
 | 
ISysFlags 8
 | 
001C7 | 
 DA1NoChMASK
 | 
DA1 not changed <see>SysNib8
 | 
002C7 | 
 DA2aNoChMASK
 | 
DA2a not changed <see>SysNib8
 | 
004C7 | 
 DA2bNoChMASK
 | 
DA2b not changed <see>SysNib8
 | 
008C7 | 
 DA3NoChMASK
 | 
DA3 not changed <see>SysNib8
 | 
80EC8 | 
 SysNib9
 | 
ISysFlags 9
 | 
001C8 | 
 DA1BadMASK
 | 
DA1 invalid <see>SysNib9
 | 
002C8 | 
 DA2aBadMASK
 | 
DA2a invalid <see>SysNib9
 | 
004C8 | 
 DA2bBadMASK
 | 
DA2b invalid <see>SysNib9
 | 
008C8 | 
 DA3BadMASK
 | 
DA3 invalid <see>SysNib9
 | 
80EC9 | 
 SysNib10
 | 
ISysFlags 10 
aka: EDITFLAG, EDITLFLAG
 | 
001C9 | 
 EDITLMASK
 | 
Edit line exists <see>SysNib10
 | 
002C9 | 
 NAppKeyMASK
 | 
Non-app keys allowed in POL <see>SysNib10
 | 
004C9 | 
 NUsrKeyMASK
 | 
Non-user keys allowed in USR mode 
<see>SysNib10
 | 
008C9 | 
 AppModeMASK
 | 
POL application running <see>SysNib10
 | 
80ECA | 
 SysNib11
 | 
ISysFlags 11 
aka: ParenModFLAG
 | 
001CA | 
 ParenModMASK
 | 
Implicit parenthesized "/", "^", 
and "SQRT" in EQW <see>SysNib11
 | 
002CA | 
 1PDCMASK
 | 
Partial DeCompile info will not 
be saved <see>SysNib11
 | 
004CA | 
 NewEditLMASK
 | 
New one-line edit line has been 
created <see>SysNib11
 | 
008CA | 
 DoStdKeyMASK
 | 
Do only standard keys <see>SysNib11
 | 
80ECB | 
 SysNib12
 | 
ISysFlags 12
 | 
001CB | 
 DispTimeMASK
 | 
Status bar clock may be displayed 
<see>SysNib12
 | 
002CB | 
 NOP2MASK12
 | 
unused <see>SysNib12
 | 
004CB | 
 CaseSensitiv
 | 
unused <see>SysNib12
 | 
008CB | 
 SpeedMASK
 | 
Metakernel repeat speed <see>SysNib12
 | 
80ECC | 
 SysNib13
 | 
ISysFlags 13
 | 
001CC | 
 InApletMASK
 | 
Aplet running <see>SysNib13
 | 
002CC | 
 SplitMASK
 | 
<see>SysNib13
 | 
004CC | 
 RightMASK
 | 
<see>SysNib13
 | 
008CC | 
 CurTknMASK
 | 
<see>SysNib13
 | 
80ECD | 
 SizeMLDisp
 | 
 
aka: SysNib14
 | 
80ECE | 
 SysNib15
 | 
ISysFlags 15
 | 
001CE | 
 BadTOLUIMASK
 | 
TOL UI potentially corrupt 
<see>SysNib15 
aka: NOP1MASK15
 | 
002CE | 
 NoAlgProcess
 | 
EVAL-> will not create a list nor 
return NOVAL <see>SysNib15 
aka: NOP2MASK15
 | 
004CE | 
 InSimplyExpr
 | 
<see>SysNib15 
aka: NOP4MASK15
 | 
008CE | 
 DoCreateMenu
 | 
<see>SysNib15 
aka: NOP8MASK15
 | 
80ECF | 
 SysNib16
 | 
ISysFlags 16 (unused)
 | 
001CF | 
 NOP1MASK16
 | 
<see>SysNib16
 | 
002CF | 
 NOP2MASK16
 | 
<see>SysNib16
 | 
004CF | 
 NOP4MASK16
 | 
<see>SysNib16
 | 
008CF | 
 NOP8MASK16
 | 
<see>SysNib16
 | 
80ED0 | 
 SysNib17
 | 
ISysFlags 17 (unused)
 | 
001D0 | 
 NOP1MASK17
 | 
<see>SysNib17
 | 
002D0 | 
 NOP2MASK17
 | 
<see>SysNib17
 | 
004D0 | 
 NOP4MASK17
 | 
<see>SysNib17
 | 
008D0 | 
 NOP8MASK17
 | 
<see>SysNib17
 | 
80ED1 | 
 SysNib18
 | 
ISysFlags 18 (unused)
 | 
001D1 | 
 NOP1MASK18
 | 
<see>SysNib18
 | 
002D1 | 
 NOP2MASK18
 | 
<see>SysNib18
 | 
004D1 | 
 NOP4MASK18
 | 
<see>SysNib18
 | 
008D1 | 
 NOP8MASK18
 | 
<see>SysNib18
 | 
80ED2 | 
 SysNib19
 | 
ISysFlags 19 (unused)
 | 
001D2 | 
 NOP1MASK19
 | 
<see>SysNib19
 | 
002D2 | 
 NOP2MASK19
 | 
<see>SysNib19
 | 
004D2 | 
 NOP4MASK19
 | 
<see>SysNib19
 | 
008D2 | 
 NOP8MASK19
 | 
<see>SysNib19
 | 
80ED3 | 
 SysNib20
 | 
ISysFlags 20 (unused)
 | 
001D3 | 
 NOP1MASK20
 | 
<see>SysNib20
 | 
002D3 | 
 NOP2MASK20
 | 
<see>SysNib20
 | 
004D3 | 
 NOP4MASK20
 | 
<see>SysNib20
 | 
008D3 | 
 NOP8MASK20
 | 
<see>SysNib20
 |