--- a/dmeval.h	Thu May 09 06:36:54 2013 +0300
+++ b/dmeval.h	Thu May 09 08:28:39 2013 +0300
@@ -36,7 +36,7 @@
     // Special ops
     OP_FUNC,
     OP_VAR,
-    OP_CONST,
+    OP_VALUE,
     OP_SUBEXPR,
 
     // Total number of operators
@@ -65,32 +65,34 @@
 
 enum
 {
-    ID_FUNC,
-    ID_VAR,
-    ID_CVAR,
+    SYM_FUNC,
+    SYM_VAR,
+    SYM_CVAR,
 } DMEvalSymbolType;
 
 
 typedef struct
 {
-    char *name;
-    int type;
-    int nargs;
+    char *name;     // Name of the symbol
+    int type;       // Type (SYM_*)
+    int nargs;      // Number of arguments, if SYM_FUNC
+
     DMValue (*func)(DMValue arg[DM_MAX_ARGS]);
-    DMValue *var, cvalue;
+
+    DMValue *var;   // Pointer to variable value if SYM_VAR
+    DMValue cvalue; // Const value, if SYM_CVAR
 } DMEvalSymbol;
 
 
 typedef struct DMEvalNode
 {
-    BOOL ok;
-    int op;
-    DMValue val;
-    DMEvalSymbol *id;
+    int op;               // Operator/token type
+    DMValue val;          // Value, if immediate constant 
+    DMEvalSymbol *symbol; // Symbol pointer, if function/variable/constvar
 
-    struct DMEvalNode *args[DM_MAX_ARGS];
+    struct DMEvalNode *args[DM_MAX_ARGS]; // Arguments, if function
 
-    struct DMEvalNode *subexpr, *next, *prev;
+    struct DMEvalNode *subexpr, *left, *right, *next, *prev;
 } DMEvalNode;