Available lDebug variables:
V0..VF	User-specified usage
DCO	Debugger Common Options
DAO	Debugger Assembler/disassembler Options
 The following variables cannot be written:
PSP	Debuggee Process (as real mode segment)
PPR	Debuggee's Parent Process
PPI	Debuggee's Parent Process Interrupt 22h
DIF	Debugger Internal Flags
DCS	Debugger Common Startup options
DAS	Debugger Assembler/disassembler Startup options
DPR	Debugger Process (as Real mode segment)
DPS	Debugger Process Selector (zero in real mode)
DPP	Debugger's Parent Process (zero in TSR mode)
DPI	Debugger's Parent process Interrupt 22h (zero in TSR mode)

Enter ?O to display the options and internal flags.
