Slightly reworked lexer to for a few directives:

'opt' and several other directives ('printt', 'fail' etc.) no longer causes a syntax error when unquoted.
'include', 'incdir' and 'incbin' and 'output' with '<pathname>' quotes no longer cause syntax error.

src/main/gen/de/platon42/intellij/plugins/m68k/lexer/_M68kLexer.java

@@ -867,6 +867,10 @@ public class _M68kLexer implements FlexLexer {
                             startExpr(EXPR, EXPR_OP);
                             return DATA_DIRECTIVE;
                         }
+                        if (isPlainDirective(yytext())) {
+                            yybegin(MACROCALL);
+                            return OTHER_DIRECTIVE;
+                        }
                         if (isOtherDirective(yytext())) {
                             startExpr(EXPR, EXPR_OP);
                             return OTHER_DIRECTIVE;

src/main/java/de/platon42/intellij/plugins/m68k/asm/AssemblerDirectives.kt

@@ -22,7 +22,15 @@ object AssemblerDirectives {
         "rsset", "clrfo", "clrso", "setfo", "setso"
     )
 
-    val otherDirective: Set<String> = setOf(
+    val plainDirectives: Set<String> = setOf(
+        "incdir", "include", "incbin", "output", "idnt",
+
+        "printt", "echo", "fail",
+
+        "opt"
+    )
+
+    val otherDirectives: Set<String> = setOf(
         "if",
         "ifeq", "ifne", "ifgt", "ifge", "iflt", "ifle", "ifb", "ifnb", "ifc", "ifnc",
         "ifd", "ifnd", "ifmacrod", "ifmacrond",
@@ -38,12 +46,10 @@ object AssemblerDirectives {
         "reg", "equr", "equrl",
         "freg", "fequr", "fequrl",
 
-        "incdir", "include", "incbin", "output",
-
         "list", "nlist", "nolist", "llen", "nopage", "page", "spc",
         "org",
 
-        "assert", "fail", "print", "printt", "printv", "echo",
+        "assert", "printv",
 
         "inline", "einline",
         "rem", "erem",
@@ -51,8 +57,6 @@ object AssemblerDirectives {
         "machine", "mc68000", "mc68010", "mc68020", "mc68030", "mc68040", "mc68060",
         "fpu",
 
-        "basereg", "endb", "far", "near", "initnear",
-
-        "opt"
+        "basereg", "endb", "far", "near", "initnear"
     )
 }

src/main/java/de/platon42/intellij/plugins/m68k/lexer/LexerUtil.kt

@@ -23,7 +23,10 @@ object LexerUtil {
     fun isDataDirective(text: CharSequence) = AssemblerDirectives.dataDirectives.contains(text.toString().lowercase())
 
     @JvmStatic
-    fun isOtherDirective(text: CharSequence) = AssemblerDirectives.otherDirective.contains(text.toString().lowercase())
+    fun isPlainDirective(text: CharSequence) = AssemblerDirectives.plainDirectives.contains(text.toString().lowercase())
+
+    @JvmStatic
+    fun isOtherDirective(text: CharSequence) = AssemblerDirectives.otherDirectives.contains(text.toString().lowercase())
 
     @JvmStatic
     fun pushbackAssignment(text: CharSequence): Int {

src/main/java/de/platon42/intellij/plugins/m68k/lexer/_M68kLexer.flex

@@ -1,6 +1,5 @@
 package de.platon42.intellij.plugins.m68k.lexer;
 
-import com.intellij.lexer.FlexLexer;
 import com.intellij.psi.tree.IElementType;
 
 import static com.intellij.psi.TokenType.BAD_CHARACTER;
@@ -72,7 +71,7 @@ HASH_COMMENT=([#;*].*+)
 SKIP_TO_EOL=[^\r\n]+
 PLAIN_MACRO_LINE=[^;\r\n]+
 
-%state NOSOL,INSTRPART,ASMINSTR,ASMOPS,ASMOPS_OP,ASSIGNMENT,EXPR,EXPR_OP,MACROCALL,WAITEOL,MACRODEF,MACROLINE,MACROTERMINATION,MACROWAITEOL
+%state NOSOL,INSTRPART,ASMINSTR,ASMOPS,ASMOPS_OP,ASSIGNMENT,EXPR,EXPR_OP,PLAINPARAMS,WAITEOL,MACRODEF,MACROLINE,MACROTERMINATION,MACROWAITEOL
 
 %%
 <YYINITIAL, NOSOL>
@@ -81,7 +80,7 @@ PLAIN_MACRO_LINE=[^;\r\n]+
   {HASH_COMMENT}      { yybegin(YYINITIAL); return COMMENT; }
 }
 
-<INSTRPART,ASMINSTR,MACROCALL,ASSIGNMENT,EXPR,EXPR_OP,ASMOPS,ASMOPS_OP>
+<INSTRPART,ASMINSTR,PLAINPARAMS,ASSIGNMENT,EXPR,EXPR_OP,ASMOPS,ASMOPS_OP>
 {
   {EOL}               { yybegin(YYINITIAL); return EOL; }
   {COMMENT}           { yybegin(WAITEOL); return COMMENT; }
@@ -92,7 +91,7 @@ PLAIN_MACRO_LINE=[^;\r\n]+
   {WHITE_SPACE}       { return WHITE_SPACE; }
 }
 
-<MACROCALL, EXPR, EXPR_OP, ASMOPS, ASMOPS_OP> {
+<PLAINPARAMS, EXPR, EXPR_OP, ASMOPS, ASMOPS_OP> {
   {WHITE_SPACE}       { return handleEolCommentWhitespace(this); }
 }
 
@@ -117,6 +116,7 @@ PLAIN_MACRO_LINE=[^;\r\n]+
                         if(isAsmMnemonicWithSize(yytext())) { yybegin(ASMINSTR); yypushback(2); return MNEMONIC; }
                         if(isAsmMnemonic(yytext())) { yybegin(ASMINSTR); return MNEMONIC; }
                         if(isDataDirective(yytext())) { startExpr(EXPR, EXPR_OP); return DATA_DIRECTIVE; }
+                        if(isPlainDirective(yytext())) { yybegin(PLAINPARAMS); return OTHER_DIRECTIVE; }
                         if(isOtherDirective(yytext())) { startExpr(EXPR, EXPR_OP); return OTHER_DIRECTIVE; }
                         return handleMacroMode(this);
                       }
@@ -136,7 +136,7 @@ PLAIN_MACRO_LINE=[^;\r\n]+
   {OPSIZE_L}          { return OPSIZE_L; }
 }
 
-<MACROCALL> {
+<PLAINPARAMS> {
   ","                 { return SEPARATOR; }
 
   {PLAINPARAM}        { return STRINGLIT; }