Here is a list of all files with brief descriptions:

ActivationApiContexts.hpp
ActivationFrame.cpp
ActivationFrame.hpp
ActivityDispatcher.cpp
ActivityDispatcher.hpp
ActivityManager.cpp
ActivityManager.hpp
AddressInstruction.cpp
AddressInstruction.hpp
APIDefinitions.h
APIServer.cpp
APIServer.hpp
APIServerInstance.cpp
APIServerInstance.hpp
APIServerThread.cpp
APIServerThread.hpp
unix/mac/APIService.cpp
unix/linux/APIService.cpp
unix/aix/APIService.cpp
windows/APIService.cpp
ArgumentParser.h
ArrayClass.cpp
ArrayClass.hpp
AssignmentInstruction.cpp
AssignmentInstruction.hpp
automaton.cpp
automaton.hpp
BitSet.hpp
BlockClass.cpp
BlockClass.hpp
BufferClass.cpp
BufferClass.hpp
BuiltinFunctions.cpp
BuiltinFunctions.hpp
CallbackDispatcher.cpp
CallbackDispatcher.hpp
CallContextStubs.cpp
CallInstruction.cpp
CallInstruction.hpp
callrexx1.cpp
callrexx2.c
callrxnt.c
callrxwn.c
callrxwn.h
ClassClass.cpp
ClassClass.hpp
ClassDirective.cpp
ClassDirective.hpp
ClassTypeCodes.h
Clause.cpp
Clause.hpp
ClientMessage.cpp
ClientMessage.hpp
cmdparse.cpp
CommandHandler.cpp
CommandHandler.hpp
CommandInstruction.cpp
CommandInstruction.hpp
CommonExternalFunctions.cpp
ContextApi.hpp
ContextClass.cpp
ContextClass.hpp
CPPCode.cpp
CPPCode.hpp
dblqueue.cpp
dblqueue.hpp
DeadObject.cpp
DeadObject.hpp
DirectoryClass.cpp
DirectoryClass.hpp
DoBlock.cpp
DoBlock.hpp
DoInstruction.cpp
DoInstruction.hpp
DropInstruction.cpp
DropInstruction.hpp
ElseInstruction.cpp
ElseInstruction.hpp
Encodings.hpp
EndIf.cpp
EndIf.hpp
EndInstruction.cpp
EndInstruction.hpp
unix/ErrorMessages.cpp
windows/ErrorMessages.cpp
ExitHandler.cpp
ExitHandler.hpp
ExitInstruction.cpp
ExitInstruction.hpp
ExposeInstruction.cpp
ExposeInstruction.hpp
ExpressionBaseVariable.hpp
ExpressionCompoundVariable.cpp
ExpressionCompoundVariable.hpp
ExpressionDotVariable.cpp
ExpressionDotVariable.hpp
ExpressionFunction.cpp
ExpressionFunction.hpp
ExpressionList.cpp
ExpressionList.hpp
ExpressionLogical.cpp
ExpressionLogical.hpp
ExpressionMessage.cpp
ExpressionMessage.hpp
ExpressionOperator.cpp
ExpressionOperator.hpp
ExpressionStack.cpp
ExpressionStack.hpp
ExpressionStem.cpp
ExpressionStem.hpp
ExpressionVariable.cpp
ExpressionVariable.hpp
ExtensionDirective.cpp
ExtensionDirective.hpp
unix/ExternalFunctions.cpp
windows/ExternalFunctions.cpp
FileNative.cpp
unix/FileSystem.cpp
windows/FileSystem.cpp
FlagSet.hpp
ForwardInstruction.cpp
ForwardInstruction.hpp
GlobalData.cpp
GlobalNames.cpp
GlobalNames.h
GlobalProtectedObject.hpp
GuardInstruction.cpp
GuardInstruction.hpp
unix/hostemu.cpp
windows/hostemu.cpp
hostemu.h
IdentityTableClass.cpp
IdentityTableClass.hpp
IfInstruction.cpp
IfInstruction.hpp
IndirectVariableReference.cpp
IndirectVariableReference.hpp
InstructionParser.cpp
IntegerClass.cpp
IntegerClass.hpp
InternalPackage.cpp
Interpreter.cpp
Interpreter.hpp
InterpreterAPI.cpp
InterpreterInstance.cpp
InterpreterInstance.hpp
InterpreterInstanceStubs.cpp
InterpretInstruction.cpp
InterpretInstruction.hpp
KeywordConstants.cpp
LabelInstruction.cpp
LabelInstruction.hpp
LeaveInstruction.cpp
LeaveInstruction.hpp
LibraryDirective.cpp
LibraryDirective.hpp
LibraryPackage.cpp
LibraryPackage.hpp
ListClass.cpp
ListClass.hpp
LocalAPIContext.cpp
LocalAPIContext.hpp
LocalAPIManager.cpp
LocalAPIManager.hpp
LocalAPISubsystem.hpp
LocalMacroSpaceManager.cpp
LocalMacroSpaceManager.hpp
LocalQueueManager.cpp
LocalQueueManager.hpp
LocalRegistrationManager.cpp
LocalRegistrationManager.hpp
MacroSpaceApi.cpp
MacroSpaceManager.cpp
MacroSpaceManager.hpp
MemorySegment.cpp
MemorySegment.hpp
MemoryStats.cpp
MemoryStats.hpp
unix/MemorySupport.cpp
windows/MemorySupport.cpp
MessageClass.cpp
MessageClass.hpp
MessageDispatcher.cpp
MessageDispatcher.hpp
MessageInstruction.cpp
MessageInstruction.hpp
MethodClass.cpp
MethodClass.hpp
MethodContextStubs.cpp
unix/MiscSystem.cpp
windows/MiscSystem.cpp
MutableBufferClass.cpp
MutableBufferClass.hpp
NativeFunctions.h
NativeMethods.h
NopInstruction.cpp
NopInstruction.hpp
NumberStringClass.cpp
NumberStringClass.hpp
NumberStringMath.cpp
NumberStringMath.hpp
NumberStringMath2.cpp
NumericInstruction.cpp
NumericInstruction.hpp
Numerics.cpp
Numerics.hpp
ObjectClass.cpp
ObjectClass.hpp
oorexxapi.h
oorexxerrors.h
OptionsInstruction.cpp
OptionsInstruction.hpp
orxncurses.cpp
OtherwiseInstruction.cpp
OtherwiseInstruction.hpp
PackageClass.cpp
PackageClass.hpp
PackageManager.cpp
PackageManager.hpp
ParseInstruction.cpp
ParseInstruction.hpp
ParseTarget.cpp
ParseTarget.hpp
ParseTrigger.cpp
ParseTrigger.hpp
unix/PlatformDefinitions.h
windows/PlatformDefinitions.h
PointerClass.cpp
PointerClass.hpp
PrimitiveBehaviourNames.h
PrimitiveBehaviours.cpp
ProcedureInstruction.cpp
ProcedureInstruction.hpp
ProgramMetaData.cpp
ProgramMetaData.hpp
ProtectedObject.cpp
ProtectedObject.hpp
QueueClass.cpp
QueueClass.hpp
QueueInstruction.cpp
QueueInstruction.hpp
QueueManager.cpp
QueueManager.hpp
QueuesAPI.cpp
RaiseInstruction.cpp
RaiseInstruction.hpp
regexp.hpp
RegistrationAPI.cpp
RegistrationManager.cpp
RegistrationManager.hpp
RegistrationTable.cpp
RegistrationTable.hpp
RelationClass.cpp
RelationClass.hpp
ReplyInstruction.cpp
ReplyInstruction.hpp
RequiresDirective.cpp
RequiresDirective.hpp
ReturnInstruction.cpp
ReturnInstruction.hpp
unix/rexx.cpp
windows/rexx.cpp
rexx.h
RexxActivation.cpp
RexxActivation.hpp
RexxActivationStack.cpp
RexxActivationStack.hpp
RexxActivity.cpp
RexxActivity.hpp
RexxAPI.h
rexxapi1.c
rexxapi2.c
rexxapi3.c
rexxapidefs.h
unix/rexxapitypes.h
windows/rexxapitypes.h
rexxasp1.c
rexxasp2.c
rexxasp3.c
RexxBehaviour.cpp
RexxBehaviour.hpp
RexxCode.cpp
RexxCode.hpp
RexxCollection.cpp
RexxCollection.hpp
unix/RexxCompiler.cpp
windows/RexxCompiler.cpp
RexxCompoundElement.cpp
RexxCompoundElement.hpp
RexxCompoundTable.cpp
RexxCompoundTable.hpp
RexxCompoundTail.cpp
RexxCompoundTail.hpp
RexxConstants.hpp
RexxCore.h
RexxDateTime.cpp
RexxDateTime.hpp
RexxDirective.hpp
RexxEnvelope.cpp
RexxEnvelope.hpp
RexxErrorCodes.h
rexxexit.c
RexxHashTable.cpp
RexxHashTable.hpp
rexxhide.cpp
rexximage.cpp
RexxInstruction.cpp
RexxInstruction.hpp
RexxInternalApis.h
RexxInternalStack.cpp
RexxInternalStack.hpp
RexxListTable.cpp
RexxListTable.hpp
RexxLocalVariables.cpp
RexxLocalVariables.hpp
RexxMain.cpp
RexxMemory.cpp
RexxMemory.hpp
RexxMessageNumbers.h
RexxMessageTable.h
RexxMisc.cpp
RexxMisc.hpp
RexxNativeActivation.cpp
RexxNativeActivation.hpp
RexxNativeCode.cpp
RexxNativeCode.hpp
rexxpaws.cpp
unix/rexxplatformapis.h
windows/rexxplatformapis.h
RexxPlatformDefinitions.h
unix/rexxplatformdefs.h
windows/rexxplatformdefs.h
RexxQueueMethods.cpp
RexxSmartBuffer.cpp
RexxSmartBuffer.hpp
RexxStartDispatcher.cpp
RexxStartDispatcher.hpp
unix/rexxutil.cpp
windows/rexxutil.cpp
RexxVariable.cpp
RexxVariable.hpp
RexxVariableDictionary.cpp
RexxVariableDictionary.hpp
RoutineClass.cpp
RoutineClass.hpp
runRexxProgram.cpp
rxmath.cpp
unix/rxqueue.cpp
windows/rxqueue.cpp
rxregexp.cpp
rxsock.cpp
rxsock.h
rxsockfn.cpp
Rxstring.hpp
unix/rxsubcom.cpp
windows/rxsubcom.cpp
rxunixsys.cpp
rxunixsys.h
rxwinsys.cpp
SayInstruction.cpp
SayInstruction.hpp
Scanner.cpp
SecurityManager.cpp
SecurityManager.hpp
SelectInstruction.cpp
SelectInstruction.hpp
ServiceException.hpp
ServiceMessage.cpp
ServiceMessage.hpp
Setup.cpp
SignalInstruction.cpp
SignalInstruction.hpp
SourceFile.cpp
SourceFile.hpp
SourceLocation.hpp
StackClass.cpp
StackClass.hpp
StackFrameClass.cpp
StackFrameClass.hpp
stackOverflow.cpp
StemClass.cpp
StemClass.hpp
StreamCommandParser.cpp
StreamCommandParser.h
StreamNative.cpp
StreamNative.hpp
StringClass.cpp
StringClass.hpp
StringClassBit.cpp
StringClassConversion.cpp
StringClassMisc.cpp
StringClassSub.cpp
StringClassUtil.cpp
StringClassWord.cpp
StringUtil.cpp
StringUtil.hpp
SupplierClass.cpp
SupplierClass.hpp
SynchronizedBlock.hpp
unix/SysActivity.cpp
windows/SysActivity.cpp
unix/SysActivity.hpp
windows/SysActivity.hpp
unix/SysAPIManager.cpp
windows/SysAPIManager.cpp
unix/SysAPIManager.hpp
windows/SysAPIManager.hpp
unix/SysCSStream.cpp
windows/SysCSStream.cpp
unix/SysCSStream.hpp
windows/SysCSStream.hpp
unix/SysDebug.cpp
windows/SysDebug.cpp
unix/SysDebug.hpp
windows/SysDebug.hpp
unix/SysFile.cpp
windows/SysFile.cpp
unix/SysFile.hpp
windows/SysFile.hpp
unix/SysFileSystem.cpp
windows/SysFileSystem.cpp
unix/SysFileSystem.hpp
windows/SysFileSystem.hpp
unix/SysInterpreterInstance.cpp
windows/SysInterpreterInstance.cpp
unix/SysInterpreterInstance.hpp
windows/SysInterpreterInstance.hpp
unix/SysLegacyAPI.cpp
windows/SysLegacyAPI.cpp
unix/SysLibrary.cpp
windows/SysLibrary.cpp
unix/SysLibrary.hpp
windows/SysLibrary.hpp
unix/SysLocalAPIManager.cpp
windows/SysLocalAPIManager.cpp
unix/SysLocalAPIManager.hpp
windows/SysLocalAPIManager.hpp
unix/SysNativeFunctions.h
windows/SysNativeFunctions.h
unix/SysNativeMethods.h
windows/SysNativeMethods.h
unix/SysProcess.cpp
windows/SysProcess.cpp
unix/SysProcess.hpp
windows/SysProcess.hpp
unix/SysSemaphore.cpp
windows/SysSemaphore.cpp
unix/SysSemaphore.hpp
windows/SysSemaphore.hpp
unix/SystemCommands.cpp
windows/SystemCommands.cpp
unix/SystemInitialization.cpp
windows/SystemInitialization.cpp
unix/SystemInterpreter.cpp
windows/SystemInterpreter.cpp
unix/SystemInterpreter.hpp
windows/SystemInterpreter.hpp
unix/SysThread.cpp
windows/SysThread.cpp
unix/SysThread.hpp
windows/SysThread.hpp
unix/SysUtilities.cpp
windows/SysUtilities.cpp
TableClass.cpp
TableClass.hpp
TextClass.cpp
TextClass.hpp
ThenInstruction.cpp
ThenInstruction.hpp
ThreadContextStubs.cpp
unix/TimeSupport.cpp
windows/TimeSupport.cpp
Token.cpp
Token.hpp
TraceInstruction.cpp
TraceInstruction.hpp
TranslateDispatcher.cpp
TranslateDispatcher.hpp
TrappingDispatcher.cpp
TrappingDispatcher.hpp
UninitDispatcher.cpp
UninitDispatcher.hpp
UpperInstruction.cpp
UpperInstruction.hpp
unix/UseridFunction.cpp
windows/UseridFunction.cpp
UseStrictInstruction.cpp
UseStrictInstruction.hpp
Utilities.cpp
Utilities.hpp
unix/ValueFunction.cpp
windows/ValueFunction.cpp
Version.cpp
VirtualFunctionTable.cpp
WeakReferenceClass.cpp
WeakReferenceClass.hpp