diff --git a/src/alu.c b/src/alu.c
index fb12587..c96aa09 100644
--- a/src/alu.c
+++ b/src/alu.c
@@ -162,8 +162,8 @@ enum alu_state {
 };
 static enum alu_state	alu_state;	// deterministic finite automaton
 // predefined stuff
-static struct node_t	*operator_tree	= NULL;	// tree to hold operators
-static struct node_t	operator_list[]	= {
+static struct ronode	*operator_tree	= NULL;	// tree to hold operators
+static struct ronode	operator_list[]	= {
 	PREDEFNODE(s_asr,	&ops_asr),
 	PREDEFNODE(s_lsr,	&ops_lsr),
 	PREDEFNODE(s_asl,	&ops_sl),
@@ -176,8 +176,8 @@ static struct node_t	operator_list[]	= {
 	PREDEFLAST(s_xor,	&ops_xor),
 	//    ^^^^ this marks the last element
 };
-static struct node_t	*function_tree	= NULL;	// tree to hold functions
-static struct node_t	function_list[]	= {
+static struct ronode	*function_tree	= NULL;	// tree to hold functions
+static struct ronode	function_list[]	= {
 	PREDEFNODE("addr",	&ops_addr),
 	PREDEFNODE("int",	&ops_int),
 	PREDEFNODE("float",	&ops_float),
diff --git a/src/basics.c b/src/basics.c
index 206fb35..e50cbef 100644
--- a/src/basics.c
+++ b/src/basics.c
@@ -240,7 +240,7 @@ static enum eos PO_serious(void)
 
 
 // pseudo ocpode table
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE(s_08,	PO_08),
 	PREDEFNODE(s_8,		PO_08),
 	PREDEFNODE("by",	PO_08),
diff --git a/src/cpu.c b/src/cpu.c
index 393f3de..ca9af44 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -60,8 +60,8 @@ static struct cpu_type	cpu_type_65816	= {
 // variables
 
 // predefined stuff
-static struct node_t	*CPU_tree	= NULL;	// tree to hold CPU types
-static struct node_t	CPUs[]	= {
+static struct ronode	*CPU_tree	= NULL;	// tree to hold CPU types
+static struct ronode	CPUs[]	= {
 //	PREDEFNODE("z80",		&cpu_type_Z80),
 	PREDEFNODE("6502",		&cpu_type_6502),
 	PREDEFNODE("6510",		&cpu_type_6510),
@@ -230,7 +230,7 @@ static enum eos PO_rs(void)
 
 // pseudo opcode table
 // FIXME - move to basics.c
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE("align",	PO_align),
 	PREDEFNODE("cpu",	PO_cpu),
 	PREDEFNODE("pseudopc",	PO_pseudopc),
diff --git a/src/encoding.c b/src/encoding.c
index e61e29f..7fe418a 100644
--- a/src/encoding.c
+++ b/src/encoding.c
@@ -29,7 +29,7 @@ static const char	s_scr[]		= "scr";
 static char	outermost_table[256];	// space for encoding table...
 static char	*loaded_table	= outermost_table;	// ...loaded from file
 // predefined stuff
-static struct node_t	*encoder_tree	= NULL;	// tree to hold encoders
+static struct ronode	*encoder_tree	= NULL;	// tree to hold encoders
 
 
 // Functions
@@ -216,7 +216,7 @@ static enum eos PO_convtab(void)
 }
 
 // pseudo opcode table
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE(s_cbm,	PO_cbm),
 	PREDEFNODE("ct",	PO_convtab),
 	PREDEFNODE("convtab",	PO_convtab),
@@ -230,7 +230,7 @@ static struct node_t	pseudo_opcodes[]	= {
 };
 
 // keywords for "!convtab" pseudo opcode
-static struct node_t	encoders[]	= {
+static struct ronode	encoders[]	= {
 	PREDEFNODE(s_pet,	encoder_pet),
 	PREDEFNODE(s_raw,	encoder_raw),
 	PREDEFLAST(s_scr,	encoder_scr),
diff --git a/src/flow.c b/src/flow.c
index 1b71194..e06a75b 100644
--- a/src/flow.c
+++ b/src/flow.c
@@ -36,8 +36,8 @@ struct loop_condition {
 // variables
 
 // predefined stuff
-static struct node_t	*condkey_tree	= NULL;	// tree to hold UNTIL and WHILE
-static struct node_t	condkeys[]	= {
+static struct ronode	*condkey_tree	= NULL;	// tree to hold UNTIL and WHILE
+static struct ronode	condkeys[]	= {
 	PREDEFNODE("until",	TRUE),	// UNTIL inverts the condition
 	PREDEFLAST("while",	FALSE),	// WHILE does not change the condition
 	//    ^^^^ this marks the last element
@@ -336,10 +336,10 @@ static enum eos PO_if(void)	// Now GotByte = illegal char
 // conditional assembly ("!ifdef" and "!ifndef"). Has to be re-entrant.
 static enum eos ifdef_ifndef(int invert)	// Now GotByte = illegal char
 {
-	struct node_ra_t	*node;
-	struct symbol		*symbol;
-	zone_t			zone;
-	int			defined	= FALSE;
+	struct rwnode	*node;
+	struct symbol	*symbol;
+	zone_t		zone;
+	int		defined	= FALSE;
 
 	if (Input_read_zone_and_keyword(&zone) == 0)	// skips spaces before
 		return SKIP_REMAINDER;
@@ -453,7 +453,7 @@ static enum eos PO_source(void)	// Now GotByte = illegal char
 
 
 // pseudo opcode table
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE("do",	PO_do),
 	PREDEFNODE("for",	PO_for),
 	PREDEFNODE("if",	PO_if),
diff --git a/src/global.c b/src/global.c
index 30f0080..5de69ad 100644
--- a/src/global.c
+++ b/src/global.c
@@ -98,7 +98,7 @@ const char	Byte_flags[256]	= {
 
 
 // variables
-struct node_t	*pseudo_opcode_tree	= NULL;	// tree to hold pseudo opcodes
+struct ronode	*pseudo_opcode_tree	= NULL;	// tree to hold pseudo opcodes (FIXME - move when grouping all POs)
 int		pass_count;			// number of current pass (starts 0)
 char		GotByte;			// Last byte read (processed)
 int		Process_verbosity	= 0;	// Level of additional output
diff --git a/src/global.h b/src/global.h
index f5bd282..1050be9 100644
--- a/src/global.h
+++ b/src/global.h
@@ -56,7 +56,7 @@ extern const char	Byte_flags[];
 
 // Variables
 
-extern struct node_t	*pseudo_opcode_tree;	// tree to hold pseudo opcodes
+extern struct ronode	*pseudo_opcode_tree;	// tree to hold pseudo opcodes (FIXME - move when grouping all POs)
 // structures
 // different ways to handle end-of-statement:
 enum eos {
diff --git a/src/input.c b/src/input.c
index 9d5c662..3e7ee81 100644
--- a/src/input.c
+++ b/src/input.c
@@ -51,7 +51,7 @@ static enum eos PO_eof(void)
 }
 
 // predefined stuff
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE("eof",	PO_eof),
 	PREDEFLAST("endoffile",	PO_eof),
 	//    ^^^^ this marks the last element
diff --git a/src/macro.c b/src/macro.c
index c731b13..8637b3c 100644
--- a/src/macro.c
+++ b/src/macro.c
@@ -50,7 +50,7 @@ union macro_arg_t {
 // Variables
 static struct dynabuf	*user_macro_name;	// original macro title
 static struct dynabuf	*internal_name;		// plus param type chars
-static struct node_ra_t	*macro_forest[256];	// trees (because of 8b hash)
+static struct rwnode	*macro_forest[256];	// trees (because of 8b hash)
 // Dynamic argument table
 static union macro_arg_t	*arg_table	= NULL;
 static int			argtable_size	= HALF_INITIAL_ARG_TABLE_SIZE;
@@ -125,7 +125,7 @@ static char *get_string_copy(const char *original)
 // Terminate macro name and copy from internal_name to GlobalDynaBuf
 // (because that's where Tree_hard_scan() looks for the search string).
 // Then try to find macro and return whether it was created.
-static int search_for_macro(struct node_ra_t **result, zone_t zone, int create)
+static int search_for_macro(struct rwnode **result, zone_t zone, int create)
 {
 	DynaBuf_append(internal_name, '\0');	// terminate macro name
 	// now internal_name = macro_title SPC argument_specifiers NUL
@@ -139,7 +139,7 @@ static int search_for_macro(struct node_ra_t **result, zone_t zone, int create)
 // It first outputs a warning and then a serious error, stopping assembly.
 // Showing the first message as a warning guarantees that ACME does not reach
 // the maximum error limit inbetween.
-static void report_redefinition(struct node_ra_t *macro_node)
+static void report_redefinition(struct rwnode *macro_node)
 {
 	struct macro	*original_macro	= macro_node->body;
 
@@ -160,10 +160,10 @@ static void report_redefinition(struct node_ra_t *macro_node)
 // Return with GotByte = '}'
 void Macro_parse_definition(void)	// Now GotByte = illegal char after "!macro"
 {
-	char			*formal_parameters;
-	struct node_ra_t	*macro_node;
-	struct macro		*new_macro;
-	zone_t			macro_zone	= get_zone_and_title();
+	char		*formal_parameters;
+	struct rwnode	*macro_node;
+	struct macro	*new_macro;
+	zone_t		macro_zone	= get_zone_and_title();
 
 	// now GotByte = first non-space after title
 	DYNABUF_CLEAR(GlobalDynaBuf);	// prepare to hold formal parameters
@@ -224,15 +224,15 @@ void Macro_parse_definition(void)	// Now GotByte = illegal char after "!macro"
 // Parse macro call ("+MACROTITLE"). Has to be re-entrant.
 void Macro_parse_call(void)	// Now GotByte = dot or first char of macro name
 {
-	char			local_gotbyte;
-	struct symbol		*symbol;
-	struct section		new_section,
-				*outer_section;
-	struct input		new_input,
-				*outer_input;
-	struct macro		*actual_macro;
-	struct node_ra_t	*macro_node,
-				*symbol_node;
+	char		local_gotbyte;
+	struct symbol	*symbol;
+	struct section	new_section,
+			*outer_section;
+	struct input	new_input,
+			*outer_input;
+	struct macro	*actual_macro;
+	struct rwnode	*macro_node,
+			*symbol_node;
 	zone_t		macro_zone,
 			symbol_zone;
 	int		arg_count	= 0;
diff --git a/src/mnemo.c b/src/mnemo.c
index a10670f..c7b5e01 100644
--- a/src/mnemo.c
+++ b/src/mnemo.c
@@ -144,13 +144,13 @@ static const char	exception_highbyte_zero[]	= "Using oversized addressing mode."
 
 static struct dynabuf	*mnemo_dyna_buf;	// dynamic buffer for mnemonics
 // predefined stuff
-static struct node_t	*mnemo_6502_tree	= NULL;	// holds 6502 mnemonics
-static struct node_t	*mnemo_6510_tree	= NULL;	// holds 6510 extensions
-static struct node_t	*mnemo_c64dtv2_tree	= NULL;	// holds C64DTV2 extensions
-static struct node_t	*mnemo_65c02_tree	= NULL;	// holds 65c02 extensions
-//static struct node_t	*mnemo_Rockwell65c02_tree	= NULL;	// Rockwell
-static struct node_t	*mnemo_WDC65c02_tree	= NULL;	// WDC's "stp"/"wai"
-static struct node_t	*mnemo_65816_tree	= NULL;	// holds 65816 extensions
+static struct ronode	*mnemo_6502_tree	= NULL;	// holds 6502 mnemonics
+static struct ronode	*mnemo_6510_tree	= NULL;	// holds 6510 extensions
+static struct ronode	*mnemo_c64dtv2_tree	= NULL;	// holds C64DTV2 extensions
+static struct ronode	*mnemo_65c02_tree	= NULL;	// holds 65c02 extensions
+//static struct ronode	*mnemo_Rockwell65c02_tree	= NULL;	// Rockwell
+static struct ronode	*mnemo_WDC65c02_tree	= NULL;	// WDC's "stp"/"wai"
+static struct ronode	*mnemo_65816_tree	= NULL;	// holds 65816 extensions
 
 // Command's code and group values are stored together in a single integer.
 // To extract the code, use "& CODEMASK".
@@ -162,7 +162,7 @@ static struct node_t	*mnemo_65816_tree	= NULL;	// holds 65816 extensions
 #define GROUPSHIFT	10	// shift right by this to extract group
 #define MERGE(g, v)	((g << GROUPSHIFT) | v)
 
-static struct node_t	mnemos_6502[]	= {
+static struct ronode	mnemos_6502[]	= {
 	PREDEFNODE("ora", MERGE(GROUP_ACCU, IDX_ORA | IMM_ACCU)),
 	PREDEFNODE(s_and, MERGE(GROUP_ACCU, IDX_AND | IMM_ACCU)),
 	PREDEFNODE(s_eor, MERGE(GROUP_ACCU, IDX_EOR | IMM_ACCU)),
@@ -222,7 +222,7 @@ static struct node_t	mnemos_6502[]	= {
 	//    ^^^^ this marks the last element
 };
 
-static struct node_t	mnemos_6510[]	= {
+static struct ronode	mnemos_6510[]	= {
 	PREDEFNODE("slo", MERGE(GROUP_ACCU, IDX_SLO)),	// ASL + ORA (aka ASO)
 	PREDEFNODE("rla", MERGE(GROUP_ACCU, IDX_RLA)),	// ROL + AND
 	PREDEFNODE("sre", MERGE(GROUP_ACCU, IDX_SRE)),	// LSR + EOR (aka LSE)
@@ -242,14 +242,14 @@ static struct node_t	mnemos_6510[]	= {
 	//    ^^^^ this marks the last element
 };
 
-static struct node_t	mnemos_c64dtv2[]	= {
+static struct ronode	mnemos_c64dtv2[]	= {
 	PREDEFNODE(s_bra, MERGE(GROUP_RELATIVE8,  0x12)),	// branch always
 	PREDEFNODE("sac", MERGE(GROUP_MISC, IDX_SAC)),	// set accumulator mapping
 	PREDEFLAST("sir", MERGE(GROUP_MISC, IDX_SIR)),	// set index register mapping
 	//    ^^^^ this marks the last element
 };
 
-static struct node_t	mnemos_65c02[]	= {
+static struct ronode	mnemos_65c02[]	= {
 	PREDEFNODE("ora", MERGE(GROUP_ACCU,	IDXcORA | IMM_ACCU)),
 	PREDEFNODE(s_and, MERGE(GROUP_ACCU,	IDXcAND | IMM_ACCU)),
 	PREDEFNODE(s_eor, MERGE(GROUP_ACCU,	IDXcEOR | IMM_ACCU)),
@@ -273,7 +273,7 @@ static struct node_t	mnemos_65c02[]	= {
 	//    ^^^^ this marks the last element
 };
 
-//static struct node_t	mnemos_Rockwell65c02[]	= {
+//static struct ronode	mnemos_Rockwell65c02[]	= {
 //	PREDEFNODE("rmb0", MERGE(G_	, 0x07)),
 //	PREDEFNODE("rmb1", MERGE(G_	, 0x17)),
 //	PREDEFNODE("rmb2", MERGE(G_	, 0x27)),
@@ -309,13 +309,13 @@ static struct node_t	mnemos_65c02[]	= {
 //	//    ^^^^ this marks the last element
 //};
 
-static struct node_t	mnemos_WDC65c02[]	= {
+static struct ronode	mnemos_WDC65c02[]	= {
 	PREDEFNODE("stp", MERGE(GROUP_IMPLIEDONLY, 219)),
 	PREDEFLAST("wai", MERGE(GROUP_IMPLIEDONLY, 203)),
 	//    ^^^^ this marks the last element
 };
 
-static struct node_t	mnemos_65816[]	= {
+static struct ronode	mnemos_65816[]	= {
 	PREDEFNODE("ora", MERGE(GROUP_ACCU,	IDX816ORA | IMM_ACCU)),
 	PREDEFNODE(s_and, MERGE(GROUP_ACCU,	IDX816AND | IMM_ACCU)),
 	PREDEFNODE(s_eor, MERGE(GROUP_ACCU,	IDX816EOR | IMM_ACCU)),
@@ -838,7 +838,7 @@ static void group_jump(int index)
 }
 
 // Work function
-static int check_mnemo_tree(struct node_t *tree, struct dynabuf *dyna_buf)
+static int check_mnemo_tree(struct ronode *tree, struct dynabuf *dyna_buf)
 {
 	void	*node_body;
 	int	code,
diff --git a/src/output.c b/src/output.c
index ddf03a6..a78da44 100644
--- a/src/output.c
+++ b/src/output.c
@@ -59,7 +59,7 @@ struct vcpu		CPU_state;	// current CPU state
 
 // FIXME - move file format stuff to some other .c file!
 // predefined stuff
-static struct node_t	*file_format_tree	= NULL;	// tree to hold output formats
+static struct ronode	*file_format_tree	= NULL;	// tree to hold output formats
 // possible file formats
 enum output_format {
 	OUTPUT_FORMAT_UNSPECIFIED,	// default (uses "plain" actually)
@@ -67,7 +67,7 @@ enum output_format {
 	OUTPUT_FORMAT_CBM,		// load address, code (default for "!to" pseudo opcode)
 	OUTPUT_FORMAT_PLAIN		// code only
 };
-static struct node_t	file_formats[]	= {
+static struct ronode	file_formats[]	= {
 	PREDEFNODE("apple",	OUTPUT_FORMAT_APPLE),
 	PREDEFNODE(s_cbm,	OUTPUT_FORMAT_CBM),
 //	PREDEFNODE("o65",	OUTPUT_FORMAT_O65),
@@ -79,11 +79,11 @@ static enum output_format	output_format	= OUTPUT_FORMAT_UNSPECIFIED;
 
 
 // predefined stuff
-static struct node_t	*segment_modifier_tree	= NULL;	// tree to hold segment modifiers
+static struct ronode	*segment_modifier_tree	= NULL;	// tree to hold segment modifiers
 // segment modifiers
 #define	SEGMENT_FLAG_OVERLAY	(1u << 0)
 #define	SEGMENT_FLAG_INVISIBLE	(1u << 1)
-static struct node_t	segment_modifiers[]	= {
+static struct ronode	segment_modifiers[]	= {
 	PREDEFNODE("overlay",	SEGMENT_FLAG_OVERLAY),
 	PREDEFLAST("invisible",	SEGMENT_FLAG_INVISIBLE),
 	//    ^^^^ this marks the last element
@@ -350,7 +350,7 @@ static enum eos PO_to(void)
 
 // pseudo ocpode table
 // FIXME - move to basics.c
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE("initmem",	PO_initmem),
 	PREDEFLAST("to",	PO_to),
 	//    ^^^^ this marks the last element
diff --git a/src/section.c b/src/section.c
index 3cb68d0..51888ed 100644
--- a/src/section.c
+++ b/src/section.c
@@ -97,7 +97,7 @@ static enum eos PO_subzone(void)
 }
 
 // predefined stuff
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE(s_zone,	PO_zone),
 	PREDEFNODE("zn",	PO_zone),
 	PREDEFNODE(s_subzone,	PO_subzone),
diff --git a/src/symbol.c b/src/symbol.c
index 8be6fcd..80869b7 100644
--- a/src/symbol.c
+++ b/src/symbol.c
@@ -26,11 +26,11 @@
 
 
 // variables
-struct node_ra_t	*symbols_forest[256];	// ... (because of 8-bit hash)
+struct rwnode	*symbols_forest[256];	// ... (because of 8-bit hash)
 
 
 // Dump symbol value and flags to dump file
-static void dump_one_symbol(struct node_ra_t *node, FILE *fd)
+static void dump_one_symbol(struct rwnode *node, FILE *fd)
 {
 	struct symbol	*symbol	= node->body;
 
@@ -68,7 +68,7 @@ static void dump_one_symbol(struct node_ra_t *node, FILE *fd)
 
 
 // output symbols in VICE format (example: "al C:09ae .nmi1")
-static void dump_vice_address(struct node_ra_t *node, FILE *fd)
+static void dump_vice_address(struct rwnode *node, FILE *fd)
 {
 	struct symbol	*symbol	= node->body;
 
@@ -78,7 +78,7 @@ static void dump_vice_address(struct node_ra_t *node, FILE *fd)
 	&& (symbol->result.addr_refs == 1))
 		fprintf(fd, "al C:%04x .%s\n", (unsigned) symbol->result.val.intval, node->id_string);
 }
-static void dump_vice_usednonaddress(struct node_ra_t *node, FILE *fd)
+static void dump_vice_usednonaddress(struct rwnode *node, FILE *fd)
 {
 	struct symbol	*symbol	= node->body;
 
@@ -89,7 +89,7 @@ static void dump_vice_usednonaddress(struct node_ra_t *node, FILE *fd)
 	&& (symbol->result.addr_refs != 1))
 		fprintf(fd, "al C:%04x .%s\n", (unsigned) symbol->result.val.intval, node->id_string);
 }
-static void dump_vice_unusednonaddress(struct node_ra_t *node, FILE *fd)
+static void dump_vice_unusednonaddress(struct rwnode *node, FILE *fd)
 {
 	struct symbol	*symbol	= node->body;
 
@@ -106,10 +106,10 @@ static void dump_vice_unusednonaddress(struct node_ra_t *node, FILE *fd)
 // the symbol name must be held in GlobalDynaBuf.
 struct symbol *symbol_find(zone_t zone, int flags)
 {
-	struct node_ra_t	*node;
-	struct symbol		*symbol;
-	int			node_created,
-				force_bits	= flags & MVALUE_FORCEBITS;
+	struct rwnode	*node;
+	struct symbol	*symbol;
+	int		node_created,
+			force_bits	= flags & MVALUE_FORCEBITS;
 
 	node_created = Tree_hard_scan(&node, symbols_forest, zone, TRUE);
 	// if node has just been created, create symbol as well
@@ -234,7 +234,7 @@ static enum eos PO_sl(void)
 
 
 // predefined stuff
-static struct node_t	pseudo_opcodes[]	= {
+static struct ronode	pseudo_opcodes[]	= {
 	PREDEFNODE("set",		PO_set),
 	PREDEFNODE("symbollist",	PO_sl),
 	PREDEFLAST(s_sl,		PO_sl),
@@ -325,8 +325,8 @@ void symbols_vicelabels(FILE *fd)
 // clear symbols forest (is done early)
 void symbols_clear_init(void)
 {
-	struct node_ra_t	**ptr;
-	int			ii;
+	struct rwnode	**ptr;
+	int		ii;
 
 	// cut down all the trees (clear pointer table)
 	ptr = symbols_forest;
diff --git a/src/symbol.h b/src/symbol.h
index 4f70fd2..4ab1052 100644
--- a/src/symbol.h
+++ b/src/symbol.h
@@ -19,7 +19,7 @@ struct symbol {
 
 
 // variables
-extern struct node_ra_t	*symbols_forest[];	// trees (because of 8-bit hash)
+extern struct rwnode	*symbols_forest[];	// trees (because of 8-bit hash)
 
 
 // clear symbol forest (is done early)
diff --git a/src/tree.c b/src/tree.c
index de3d9c7..58437cc 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -15,7 +15,7 @@
 // Compute hash value by exclusive ORing the node's ID string and write
 // output to struct.
 // This function is not allowed to change GlobalDynaBuf!
-hash_t make_hash(struct node_t *node) {
+hash_t make_hash(struct ronode *node) {
 	register char		byte;
 	register const char	*read;
 	register hash_t		tmp	= 0;
@@ -28,7 +28,7 @@ hash_t make_hash(struct node_t *node) {
 }
 
 // Link a predefined data set to a tree
-void add_node_to_tree(struct node_t **tree, struct node_t *node_to_add)
+void add_node_to_tree(struct ronode **tree, struct ronode *node_to_add)
 {
 	hash_t	hash;
 
@@ -50,7 +50,7 @@ void add_node_to_tree(struct node_t **tree, struct node_t *node_to_add)
 
 // Add predefined tree items to given tree. The PREDEF* macros set HashValue
 // to 1 in all entries but the last. The last entry contains 0.
-void Tree_add_table(struct node_t **tree, struct node_t *table_to_add)
+void Tree_add_table(struct ronode **tree, struct ronode *table_to_add)
 {
 	// Caution when trying to optimise this. :)
 	while (table_to_add->hash_value)
@@ -61,11 +61,11 @@ void Tree_add_table(struct node_t **tree, struct node_t *table_to_add)
 // Search for a given ID string in a given tree.
 // Compute the hash of the given string and then use that to try to find a
 // tree item that matches the given data (HashValue and DynaBuf-String).
-// Store "Body" component in NodeBody and return TRUE.
+// Store "body" component in node_body and return TRUE.
 // Return FALSE if no matching item found.
-int Tree_easy_scan(struct node_t *tree, void **node_body, struct dynabuf *dyna_buf)
+int Tree_easy_scan(struct ronode *tree, void **node_body, struct dynabuf *dyna_buf)
 {
-	struct node_t	wanted;	// temporary storage
+	struct ronode	wanted;	// temporary storage
 	const char	*p1,
 			*p2;
 	char		b1,
@@ -106,15 +106,15 @@ int Tree_easy_scan(struct node_t *tree, void **node_body, struct dynabuf *dyna_b
 // and then use that to try to find a tree item that matches the given data
 // (HashValue, ID_Number, GlobalDynaBuf-String). Save pointer to found tree
 // item in given location.
-// If no matching item is found, check the "Create" flag. If it is set, create
+// If no matching item is found, check the "create" flag. If it is set, create
 // a new tree item, link to tree, fill with data and store its pointer. If the
-// "Create" flag is clear, store NULL as result.
+// "create" flag is zero, store NULL as result.
 // Returns whether item was created.
-int Tree_hard_scan(struct node_ra_t **result, struct node_ra_t **forest, int id_number, int create)
+int Tree_hard_scan(struct rwnode **result, struct rwnode **forest, int id_number, int create)
 {
-	struct node_t		wanted;	// temporary storage
-	struct node_ra_t	**current_node;
-	struct node_ra_t	*new_leaf_node;
+	struct ronode	wanted;	// temporary storage
+	struct rwnode	**current_node;
+	struct rwnode	*new_leaf_node;
 	const char	*p1,
 			*p2;
 	char		b1,
@@ -178,7 +178,7 @@ int Tree_hard_scan(struct node_ra_t **result, struct node_ra_t **forest, int id_
 
 // Call given function for each object of matching type in the given tree.
 // Calls itself recursively.
-void dump_tree(struct node_ra_t *node, int id_number, void (*fn)(struct node_ra_t *, FILE *), FILE *env)
+void dump_tree(struct rwnode *node, int id_number, void (*fn)(struct rwnode *, FILE *), FILE *env)
 {
 
 	if (node->id_number == id_number)
@@ -190,7 +190,7 @@ void dump_tree(struct node_ra_t *node, int id_number, void (*fn)(struct node_ra_
 }
 
 // Calls Tree_dump_tree for each non-zero entry of the given tree table.
-void Tree_dump_forest(struct node_ra_t **forest, int id_number, void (*fn)(struct node_ra_t *, FILE *), FILE *env)
+void Tree_dump_forest(struct rwnode **forest, int id_number, void (*fn)(struct rwnode *, FILE *), FILE *env)
 {
 	int	ii;
 
diff --git a/src/tree.h b/src/tree.h
index 90a6818..f60a5c6 100644
--- a/src/tree.h
+++ b/src/tree.h
@@ -21,40 +21,40 @@
 typedef unsigned int	hash_t;
 // Must be unsigned, otherwise the hash algorithm won't be very useful!
 
-// tree node structure type definition (for easy lookups)
-struct node_t {
-	struct node_t	*greater_than;	// pointer to sub-tree
-	struct node_t	*less_than_or_equal;	// pointer to sub-tree
+// tree node structure type definition for lookups in "read-only" (i.e. keyword) trees
+struct ronode {
+	struct ronode	*greater_than;	// pointer to sub-tree
+	struct ronode	*less_than_or_equal;	// pointer to sub-tree
 	hash_t		hash_value;
 	const char	*id_string;	// name, zero-terminated
 	void		*body;		// bytes, handles or handler function
 };
 
-// tree node structure type definition (for macros/labels)
-struct node_ra_t {
-	struct node_ra_t	*greater_than;	// pointer to sub-tree
-	struct node_ra_t	*less_than_or_equal;	// pointer to sub-tree
-	hash_t			hash_value;
-	char			*id_string;	// name, zero-terminated
-	void			*body;		// macro/label body
-	unsigned int		id_number;	// zone number
+// tree node structure type definition for "read/write" items, i.e. macros/labels
+struct rwnode {
+	struct rwnode	*greater_than;	// pointer to sub-tree
+	struct rwnode	*less_than_or_equal;	// pointer to sub-tree
+	hash_t		hash_value;
+	char		*id_string;	// name, zero-terminated
+	void		*body;		// macro/label body
+	unsigned int	id_number;	// zone number
 };
 
 
 // Prototypes
 
 // Add predefined tree items to given tree.
-extern void Tree_add_table(struct node_t **tree, struct node_t *table_to_add);
-// Search for a given ID string in a given tree. Store "Body" component in
-// NodeBody and return TRUE. Return FALSE if no matching item found.
-extern int Tree_easy_scan(struct node_t *tree, void **node_body, struct dynabuf *dyna_buf);
+extern void Tree_add_table(struct ronode **tree, struct ronode *table_to_add);
+// Search for a given ID string in a given tree. Store "body" component in
+// node_body and return TRUE. Return FALSE if no matching item found.
+extern int Tree_easy_scan(struct ronode *tree, void **node_body, struct dynabuf *dyna_buf);
 // Search for a "RAM tree" item. Save pointer to found tree item in given
-// location. If no matching item is found, check the "Create" flag: If set,
+// location. If no matching item is found, check the "create" flag: If set,
 // create new tree item, link to tree, fill with data and store its pointer.
-// If "Create" is clear, store NULL. Returns whether item was created.
-extern int Tree_hard_scan(struct node_ra_t **, struct node_ra_t **, int, int);
+// If "create" is zero, store NULL. Returns whether item was created.
+extern int Tree_hard_scan(struct rwnode **result, struct rwnode **forest, int id_number, int create);
 // Calls given function for each node of each tree of given forest.
-extern void Tree_dump_forest(struct node_ra_t **, int, void (*)(struct node_ra_t *, FILE *), FILE *);
+extern void Tree_dump_forest(struct rwnode **, int, void (*)(struct rwnode *, FILE *), FILE *);
 
 
 #endif