Use OPCODE for the RETURN and CONTINUE opcodes.

src/libespeak-ng/compiledata.c

 				CompileToneSpec();
 				break;
 			case kCONTINUE:
-				*prog_out++ = i_CONTINUE;
+				*prog_out++ = OPCODE_CONTINUE;
 				DecThenCount();
 				break;
 			case kRETURN:
-				*prog_out++ = i_RETURN;
+				*prog_out++ = OPCODE_RETURN;
 				DecThenCount();
 				break;
 			case kINCLUDE:
 				if (if_level > 0)
 					error("Missing ENDIF");
 				if ((prog_out > prog_buf) && (if_stack[0].returned == 0))
-					*prog_out++ = i_RETURN;
+					*prog_out++ = OPCODE_RETURN;
 				break;
 			}
 			break;

src/libespeak-ng/synthdata.c

 			// This instruction is followed by addWav(), 2 more words
 			return 4;
 		}
-		if (instn2 == i_CONTINUE)
+		if (instn2 == OPCODE_CONTINUE)
 			return 3;
 		return 2;
 	}
 				// instructions with no operand
 				switch (data)
 				{
-				case i_RETURN:
+				case OPCODE_RETURN:
 					end_flag = 1;
 					break;
-				case i_CONTINUE:
+				case OPCODE_CONTINUE:
 					break;
 				default:
 					InvalidInstn(ph, instn);
 			param_sc = phdata->sound_param[instn2] = (instn >> 4) & 0xff;
 			prog++;
 
-			if (prog[1] != i_CONTINUE) {
+			if (prog[1] != OPCODE_CONTINUE) {
 				if (instn2 < 2) {
 					// FMT() and WAV() imply Return
 					end_flag = 1;

src/libespeak-ng/synthesize.h

 
 // instructions
 
-#define i_RETURN        0x0001
-#define i_CONTINUE      0x0002
-#define i_NOT           0x0003
+#define OPCODE_RETURN        0x0001
+#define OPCODE_CONTINUE      0x0002
 
 // Group 0 instrcutions with 8 bit operand.  These values go into bits 8-15 of the instruction
 #define i_CHANGE_PHONEME 0x01
 // conditions and jumps
 #define i_CONDITION  0x2000
 #define i_OR         0x1000  // added to i_CONDITION
+#define i_NOT        0x0003
 
 #define i_JUMP       0x6000
 #define i_JUMP_FALSE 0x6800