typedef struct ByteCode {
    TclHandle interpHandle;	/* Handle for interpreter containing the
				 * compiled code. Commands and their compile
				 * procs are specific to an interpreter so the
				 * code emitted will depend on the
				 * interpreter. */
    TCL_HASH_TYPE compileEpoch;	/* Value of iPtr->compileEpoch when this
				 * ByteCode was compiled. Used to invalidate
				 * code when, e.g., commands with compile
				 * procs are redefined. */
    Namespace *nsPtr;		/* Namespace context in which this code was
				 * compiled. If the code is executed if a
				 * different namespace, it must be
				 * recompiled. */
    TCL_HASH_TYPE nsEpoch;	/* Value of nsPtr->resolverEpoch when this
				 * ByteCode was compiled. Used to invalidate
				 * code when new namespace resolution rules
				 * are put into effect. */
    TCL_HASH_TYPE refCount;	/* Reference count: set 1 when created plus 1
				 * for each execution of the code currently
				 * active. This structure can be freed when
				 * refCount becomes zero. */
    unsigned int flags;		/* flags describing state for the codebyte.
				 * this variable holds ORed values from the
				 * TCL_BYTECODE_ masks defined above */
    const char *source;		/* The source string from which this ByteCode

				 * namespace. */
    int flags;			/* OR-ed combination of the namespace status
				 * flags NS_DYING and NS_DEAD listed below. */
    size_t activationCount;	/* Number of "activations" or active call
				 * frames for this namespace that are on the
				 * Tcl call stack. The namespace won't be
				 * freed until activationCount becomes zero. */
    TCL_HASH_TYPE refCount;	/* Count of references by namespaceName
				 * objects. The namespace can't be freed until
				 * refCount becomes zero. */
    Tcl_HashTable cmdTable;	/* Contains all the commands currently
				 * registered in the namespace. Indexed by
				 * strings; values have type (Command *).
				 * Commands imported by Tcl_Import have
				 * Command structures that point (via an

				 * commands; however, no namespace qualifiers
				 * are allowed. NULL if no export patterns are
				 * registered. */
    size_t numExportPatterns;	/* Number of export patterns currently
				 * registered using "namespace export". */
    size_t maxExportPatterns;	/* Number of export patterns for which space
				 * is currently allocated. */
    TCL_HASH_TYPE cmdRefEpoch;	/* Incremented if a newly added command
				 * shadows a command for which this namespace
				 * has already cached a Command* pointer; this
				 * causes all its cached Command* pointers to
				 * be invalidated. */
    TCL_HASH_TYPE resolverEpoch;	/* Incremented whenever (a) the name
				 * resolution rules change for this namespace
				 * or (b) a newly added command shadows a
				 * command that is compiled to bytecodes. This
				 * invalidates all byte codes compiled in the
				 * namespace, causing the code to be
				 * recompiled under the new rules.*/
    Tcl_ResolveCmdProc *cmdResProc;

    Tcl_ResolveCompiledVarProc *compiledVarResProc;
				/* If non-null, this procedure overrides the
				 * usual variable resolution mechanism in Tcl.
				 * This procedure is invoked within
				 * LookupCompiledLocal to resolve variable
				 * references within the namespace at compile
				 * time. */
    TCL_HASH_TYPE exportLookupEpoch;	/* Incremented whenever a command is added to
				 * a namespace, removed from a namespace or
				 * the exports of a namespace are changed.
				 * Allows TIP#112-driven command lists to be
				 * validated efficiently. */
    Tcl_Ensemble *ensembles;	/* List of structures that contain the details
				 * of the ensembles that are implemented on
				 * top of this namespace. */

typedef struct EnsembleConfig {
    Namespace *nsPtr;		/* The namespace backing this ensemble up. */
    Tcl_Command token;		/* The token for the command that provides
				 * ensemble support for the namespace, or NULL
				 * if the command has been deleted (or never
				 * existed; the global namespace never has an
				 * ensemble command.) */
    TCL_HASH_TYPE epoch;		/* The epoch at which this ensemble's table of
				 * exported commands is valid. */
    char **subcommandArrayPtr;	/* Array of ensemble subcommand names. At all
				 * consistent points, this will have the same
				 * number of entries as there are entries in
				 * the subcommandTable hash. */
    Tcl_HashTable subcommandTable;
				/* Hash table of ensemble subcommand names,

    void *clientData;	/* Argument to pass to proc. */
    int flags;			/* What events the trace procedure is
				 * interested in: OR-ed combination of
				 * TCL_TRACE_RENAME, TCL_TRACE_DELETE. */
    struct CommandTrace *nextPtr;
				/* Next in list of traces associated with a
				 * particular command. */
    TCL_HASH_TYPE refCount; /* Used to ensure this structure is not
				 * deleted too early. Keeps track of how many
				 * pieces of code have a pointer to this
				 * structure. */
} CommandTrace;

/*
 * When a command trace is active (i.e. its associated procedure is executing)

				 * "upvar", this field points to the
				 * referenced variable's Var struct. */
    } value;
} Var;

typedef struct VarInHash {
    Var var;
    TCL_HASH_TYPE refCount;	/* Counts number of active uses of this
				 * variable: 1 for the entry in the hash
				 * table, 1 for each additional variable whose
				 * linkPtr points here, 1 for each nested
				 * trace active on variable, and 1 if the
				 * variable is a namespace variable. This
				 * record can't be deleted until refCount
				 * becomes 0. */

 * collection of Tcl commands plus information about arguments and other local
 * variables recognized at compile time.
 */

typedef struct Proc {
    struct Interp *iPtr;	/* Interpreter for which this command is
				 * defined. */
    TCL_HASH_TYPE refCount;	/* Reference count: 1 if still present in
				 * command table plus 1 for each call to the
				 * procedure that is currently active. This
				 * structure can be freed when refCount
				 * becomes zero. */
    struct Command *cmdPtr;	/* Points to the Command structure for this
				 * procedure. This is used to get the
				 * namespace in which to execute the

/*
 * Will be grown to contain: pointers to the varnames (allocated at the end),
 * plus the init values for each variable (suitable to be memcopied on init)
 */

typedef struct LocalCache {
    TCL_HASH_TYPE refCount;
    size_t numVars;
    Tcl_Obj *varName0;
} LocalCache;

#define localName(framePtr, i) \
    ((&((framePtr)->localCachePtr->varName0))[(i)])

				 * TclArgumentBCEnter(). These will be removed
				 * by TclArgumentBCRelease. */
} CmdFrame;

typedef struct CFWord {
    CmdFrame *framePtr;		/* CmdFrame to access. */
    size_t word;			/* Index of the word in the command. */
    TCL_HASH_TYPE refCount;	/* Number of times the word is on the
				 * stack. */
} CFWord;

typedef struct CFWordBC {
    CmdFrame *framePtr;		/* CmdFrame to access. */
    size_t pc;			/* Instruction pointer of a command in
				 * ExtCmdLoc.loc[.] */

				 * from its Tcl_Command handle. NULL means
				 * that the hash table entry has been removed
				 * already (this can happen if deleteProc
				 * causes the command to be deleted or
				 * recreated). */
    Namespace *nsPtr;		/* Points to the namespace containing this
				 * command. */
    TCL_HASH_TYPE refCount;	/* 1 if in command hashtable plus 1 for each
				 * reference from a CmdName Tcl object
				 * representing a command's name in a ByteCode
				 * instruction sequence. This structure can be
				 * freed when refCount becomes zero. */
    TCL_HASH_TYPE cmdEpoch;	/* Incremented to invalidate any references
				 * that point to this command when it is
				 * renamed, deleted, hidden, or exposed. */
    CompileProc *compileProc;	/* Procedure called to compile command. NULL
				 * if no compile proc exists for command. */
    Tcl_ObjCmdProc *objProc;	/* Object-based command procedure. */
    void *objClientData;	/* Arbitrary value passed to object proc. */
    Tcl_CmdProc *proc;		/* String-based command procedure. */

				 * calling Tcl_Eval. See below for valid
				 * values. */
    LiteralTable literalTable;	/* Contains LiteralEntry's describing all Tcl
				 * objects holding literals of scripts
				 * compiled by the interpreter. Indexed by the
				 * string representations of literals. Used to
				 * avoid creating duplicate objects. */
    TCL_HASH_TYPE compileEpoch;	/* Holds the current "compilation epoch" for
				 * this interpreter. This is incremented to
				 * invalidate existing ByteCodes when, e.g., a
				 * command with a compile procedure is
				 * redefined. */
    Proc *compiledProcPtr;	/* If a procedure is being compiled, a pointer
				 * to its Proc structure; otherwise, this is
				 * NULL. Set by ObjInterpProc in tclProc.c and

 * struct is grown (reallocated and copied) as necessary to hold all the
 * list's element pointers. The struct might contain more slots than currently
 * used to hold all element pointers. This is done to make append operations
 * faster.
 */

typedef struct List {
    TCL_HASH_TYPE refCount;
    size_t maxElemCount;		/* Total number of element array slots. */
    size_t elemCount;		/* Current number of list elements. */
    int canonicalFlag;		/* Set if the string representation was
				 * derived from the list representation. May
				 * be ignored if there is no string rep at
				 * all.*/
    Tcl_Obj *elements;		/* First list element; the struct is grown to

 * to be shared among several threads. Each thread sees a (Tcl_Obj) copy of
 * the value, and the gobal value is kept as a counted string, with epoch and
 * mutex control. Each ProcessGlobalValue struct should be a static variable in
 * some file.
 */

typedef struct ProcessGlobalValue {
    TCL_HASH_TYPE epoch;		/* Epoch counter to detect changes in the
				 * global value. */
    TCL_HASH_TYPE numBytes;	/* Length of the global string. */
    char *value;		/* The global string value. */
    Tcl_Encoding encoding;	/* system encoding when global string was
				 * initialized. */
    TclInitProcessGlobalValueProc *proc;
    				/* A procedure to initialize the global string