diff --git a/spec.html b/spec.html
index 96993d1a5f..42a3a067ee 100644
--- a/spec.html
+++ b/spec.html
@@ -35458,8 +35458,15 @@ <h2>Syntax</h2>
           `\` AtomEscape[?UnicodeMode, ?NamedCaptureGroups]
           CharacterClass[?UnicodeMode, ?UnicodeSetsMode]
           `(` GroupSpecifier[?UnicodeMode]? Disjunction[?UnicodeMode, ?UnicodeSetsMode, ?NamedCaptureGroups] `)`
-          `(?` RegularExpressionFlags `:` Disjunction[?UnicodeMode, ?UnicodeSetsMode, ?NamedCaptureGroups] `)`
-          `(?` RegularExpressionFlags `-` RegularExpressionFlags `:` Disjunction[?UnicodeMode, ?UnicodeSetsMode, ?NamedCaptureGroups] `)`
+          `(?` RegularExpressionModifiers `:` Disjunction[?UnicodeMode, ?UnicodeSetsMode, ?NamedCaptureGroups] `)`
+          `(?` RegularExpressionModifiers `-` RegularExpressionModifiers `:` Disjunction[?UnicodeMode, ?UnicodeSetsMode, ?NamedCaptureGroups] `)`
+
+        RegularExpressionModifiers ::
+          [empty]
+          RegularExpressionModifiers RegularExpressionModifier
+
+        RegularExpressionModifier :: one of
+          `i` `m` `s`
 
         SyntaxCharacter :: one of
           `^` `$` `\` `.` `*` `+` `?` `(` `)` `[` `]` `{` `}` `|`
@@ -35704,25 +35711,25 @@ <h1>Static Semantics: Early Errors</h1>
             It is a Syntax Error if the MV of the first |DecimalDigits| is strictly greater than the MV of the second |DecimalDigits|.
           </li>
         </ul>
-        <emu-grammar>Atom :: `(?` RegularExpressionFlags `:` Disjunction `)`</emu-grammar>
+        <emu-grammar>Atom :: `(?` RegularExpressionModifiers `:` Disjunction `)`</emu-grammar>
         <ul>
           <li>
-            It is a Syntax Error if the source text matched by |RegularExpressionFlags| contains any code point other than `i`, `m`, or `s`, or if it contains the same code point more than once.
+            It is a Syntax Error if the source text matched by |RegularExpressionModifiers| contains the same code point more than once.
           </li>
         </ul>
-        <emu-grammar>Atom :: `(?` RegularExpressionFlags `-` RegularExpressionFlags `:` Disjunction `)`</emu-grammar>
+        <emu-grammar>Atom :: `(?` RegularExpressionModifiers `-` RegularExpressionModifiers `:` Disjunction `)`</emu-grammar>
         <ul>
           <li>
-            It is a Syntax Error if the source text matched by the first |RegularExpressionFlags| and the source text matched by the second |RegularExpressionFlags| are both empty.
+            It is a Syntax Error if the source text matched by the first |RegularExpressionModifiers| and the source text matched by the second |RegularExpressionModifiers| are both empty.
           </li>
           <li>
-            It is a Syntax Error if the source text matched by the first |RegularExpressionFlags| contains any code point other than `i`, `m`, or `s`, or if it contains the same code point more than once.
+            It is a Syntax Error if the source text matched by the first |RegularExpressionModifiers| contains the same code point more than once.
           </li>
           <li>
-            It is a Syntax Error if the source text matched by the second |RegularExpressionFlags| contains any code point other than `i`, `m`, or `s`, or if it contains the same code point more than once.
+            It is a Syntax Error if the source text matched by the second |RegularExpressionModifiers| contains the same code point more than once.
           </li>
           <li>
-            It is a Syntax Error if any code point in the source text matched by the first |RegularExpressionFlags| is also contained in the source text matched by the second |RegularExpressionFlags|.
+            It is a Syntax Error if any code point in the source text matched by the first |RegularExpressionModifiers| is also contained in the source text matched by the second |RegularExpressionModifiers|.
           </li>
         </ul>
         <emu-grammar>AtomEscape :: `k` GroupName</emu-grammar>
@@ -36905,17 +36912,17 @@ <h1>
         <emu-note>
           <p>Parentheses of the form `(` |Disjunction| `)` serve both to group the components of the |Disjunction| pattern together and to save the result of the match. The result can be used either in a backreference (`\\` followed by a non-zero decimal number), referenced in a replace String, or returned as part of an array from the regular expression matching Abstract Closure. To inhibit the capturing behaviour of parentheses, use the form `(?:` |Disjunction| `)` instead.</p>
         </emu-note>
-        <emu-grammar>Atom :: `(?` RegularExpressionFlags `:` Disjunction `)`</emu-grammar>
+        <emu-grammar>Atom :: `(?` RegularExpressionModifiers `:` Disjunction `)`</emu-grammar>
         <emu-alg>
-          1. Let _addModifiers_ be the source text matched by |RegularExpressionFlags|.
+          1. Let _addModifiers_ be the source text matched by |RegularExpressionModifiers|.
           1. Let _removeModifiers_ be the empty String.
           1. Let _modifiedRer_ be UpdateModifiers(_rer_, CodePointsToString(_addModifiers_), _removeModifiers_).
           1. Return CompileSubpattern of |Disjunction| with arguments _modifiedRer_ and _direction_.
         </emu-alg>
-        <emu-grammar>Atom :: `(?` RegularExpressionFlags `-` RegularExpressionFlags `:` Disjunction `)`</emu-grammar>
+        <emu-grammar>Atom :: `(?` RegularExpressionModifiers `-` RegularExpressionModifiers `:` Disjunction `)`</emu-grammar>
         <emu-alg>
-          1. Let _addModifiers_ be the source text matched by the first |RegularExpressionFlags|.
-          1. Let _removeModifiers_ be the source text matched by the second |RegularExpressionFlags|.
+          1. Let _addModifiers_ be the source text matched by the first |RegularExpressionModifiers|.
+          1. Let _removeModifiers_ be the source text matched by the second |RegularExpressionModifiers|.
           1. Let _modifiedRer_ be UpdateModifiers(_rer_, CodePointsToString(_addModifiers_), CodePointsToString(_removeModifiers_)).
           1. Return CompileSubpattern of |Disjunction| with arguments _modifiedRer_ and _direction_.
         </emu-alg>
@@ -49689,6 +49696,8 @@ <h1>Regular Expressions</h1>
     <emu-prodref name="Quantifier"></emu-prodref>
     <emu-prodref name="QuantifierPrefix"></emu-prodref>
     <emu-prodref name="Atom"></emu-prodref>
+    <emu-prodref name="RegularExpressionModifiers"></emu-prodref>
+    <emu-prodref name="RegularExpressionModifier"></emu-prodref>
     <emu-prodref name="SyntaxCharacter"></emu-prodref>
     <emu-prodref name="PatternCharacter"></emu-prodref>
     <emu-prodref name="AtomEscape"></emu-prodref>
@@ -49852,8 +49861,8 @@ <h2>Syntax</h2>
           `\` [lookahead == `c`]
           CharacterClass[~UnicodeMode, ~UnicodeSetsMode]
           `(` GroupSpecifier[~UnicodeMode]? Disjunction[~UnicodeMode, ~UnicodeSetsMode, ?NamedCaptureGroups] `)`
-          `(?` RegularExpressionFlags `:` Disjunction[~UnicodeMode, ~UnicodeSetsMode, ?NamedCaptureGroups] `)`
-          `(?` RegularExpressionFlags `-` RegularExpressionFlags `:` Disjunction[~UnicodeMode, ~UnicodeSetsMode, ?NamedCaptureGroups] `)`
+          `(?` RegularExpressionModifiers `:` Disjunction[~UnicodeMode, ~UnicodeSetsMode, ?NamedCaptureGroups] `)`
+          `(?` RegularExpressionModifiers `-` RegularExpressionModifiers `:` Disjunction[~UnicodeMode, ~UnicodeSetsMode, ?NamedCaptureGroups] `)`
           InvalidBracedQuantifier
           ExtendedPatternCharacter