Index: generic/tclParse.c
==================================================================
--- generic/tclParse.c
+++ generic/tclParse.c
@@ -866,20 +866,31 @@
 	if (count == 2) {
 	    /*
 	     * No hexdigits -> This is just "u".
 	     */
 	    result = 'u';
-	} else if (((result & 0xFC00) == 0xD800) && (count == 6)
+#if TCL_UTF_MAX > 3
+	} else if ((result & 0xF800) == 0xD800) {
+	    result = 0xFFFD;
+#else
+	} else if ((result & 0xFC00) == 0xDC00) {
+	    result = 0xFFFD;
+	} else if ((result & 0xFC00) == 0xD800) {
+	    if ((count == 6)
 		    && (p[5] == '\\') && (p[6] == 'u') && (numBytes >= 10)) {
-	    /* If high surrogate is immediately followed by a low surrogate
-	     * escape, combine them into one character. */
-	    int low;
-	    int count2 = ParseHex(p+7, 4, &low);
-	    if ((count2 == 4) && ((low & 0xFC00) == 0xDC00)) {
-		result = ((result & 0x3FF)<<10 | (low & 0x3FF)) + 0x10000;
-		count += count2 + 2;
-	    }
+		/* If high surrogate is immediately followed by a low surrogate
+		 * escape, combine them into one character. */
+		int low;
+		int count2 = ParseHex(p+7, 4, &low);
+		if ((count2 == 4) && ((low & 0xFC00) == 0xDC00)) {
+		    result = ((result & 0x3FF)<<10 | (low & 0x3FF)) + 0x10000;
+		    count += count2 + 2;
+		    break;
+		}
+	    }
+	    result = 0xFFFD;
+#endif
 	}
 	break;
     case 'U':
 	count += ParseHex(p+1, (numBytes > 9) ? 8 : numBytes-2, &result);
 	if (count == 2) {

Index: generic/tclUtf.c
==================================================================
--- generic/tclUtf.c
+++ generic/tclUtf.c
@@ -66,11 +66,11 @@
     1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
 /* Tcl_UtfCharComplete() might point to 2nd byte of valid 4-byte sequence */
     3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
     3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
 /* End of "continuation byte section" */
-    2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+    2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
     3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
 #if TCL_UTF_MAX > 3
     4,4,4,4,4,
 #else
     1,1,1,1,1,
@@ -85,25 +85,19 @@
     1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
 /* Tcl_UtfCharComplete() might point to 2nd byte of valid 4-byte sequence */
     3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
     3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
 /* End of "continuation byte section" */
-    2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
+    2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
     3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
 #if TCL_UTF_MAX > 3
     4,4,4,4,4,
 #else
     3,3,3,3,3,
 #endif
     1,1,1,1,1,1,1,1,1,1,1
 };
-
-/*
- * Functions used only in this module.
- */
-
-static int		Invalid(const char *src);
 
 /*
  *---------------------------------------------------------------------------
  *
  * TclUtfCount --
@@ -132,66 +126,10 @@
     if (((unsigned)(ch - 0x10000) <= 0xFFFFF)) {
 	return 4;
     }
     return 3;
 }
-
-/*
- *---------------------------------------------------------------------------
- *
- * Invalid --
- *
- *	Given a pointer to a two-byte prefix of a well-formed UTF-8 byte
- *	sequence (a lead byte followed by a trail byte) this routine
- *	examines those two bytes to determine whether the sequence is
- *	invalid in UTF-8.  This might be because it is an overlong
- *	encoding, or because it encodes something out of the proper range.
- *
- *	Given a pointer to the bytes \xF8 or \xFC , this routine will
- *	try to read beyond the end of the "bounds" table.  Callers must
- *	prevent this.
- *
- *	Given a pointer to something else (an ASCII byte, a trail byte,
- *	or another byte	that can never begin a valid byte sequence such
- *	as \xF5) this routine returns false.  That makes the routine poorly
- *	named, as it does not detect and report all invalid sequences.
- *
- *	Callers have to take care that this routine does something useful
- *	for their needs.
- *
- * Results:
- *	A boolean.
- *---------------------------------------------------------------------------
- */
-
-static const unsigned char bounds[28] = {
-    0x80, 0x80,		/* \xC0 accepts \x80 only */
-    0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF,
-    0x80, 0xBF,		/* (\xC4 - \xDC) -- all sequences valid */
-    0xA0, 0xBF,	/* \xE0\x80 through \xE0\x9F are invalid prefixes */
-    0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF, /* (\xE4 - \xEC) -- all valid */
-    0x90, 0xBF,	/* \xF0\x80 through \xF0\x8F are invalid prefixes */
-    0x80, 0x8F  /* \xF4\x90 and higher are invalid prefixes */
-};
-
-static int
-Invalid(
-    const char *src)	/* Points to lead byte of a UTF-8 byte sequence */
-{
-    unsigned char byte = UCHAR(*src);
-    int index;
-
-    if ((byte & 0xC3) == 0xC0) {
-	/* Only lead bytes 0xC0, 0xE0, 0xF0, 0xF4 need examination */
-	index = (byte - 0xC0) >> 1;
-	if (UCHAR(src[1]) < bounds[index] || UCHAR(src[1]) > bounds[index+1]) {
-	    /* Out of bounds - report invalid. */
-	    return 1;
-	}
-    }
-    return 0;
-}
 
 /*
  *---------------------------------------------------------------------------
  *
  * Tcl_UniCharToUtf --
@@ -499,10 +437,13 @@
 	     */
 
 	    *chPtr = (((byte & 0x0F) << 12)
 		    | ((src[1] & 0x3F) << 6) | (src[2] & 0x3F));
 	    if (*chPtr > 0x7FF) {
+		if ((*chPtr & 0xF800) == 0xD800) {
+		    *chPtr = 0xFFFD;
+		}
 		return 3;
 	    }
 	}
 
 	/*
@@ -595,10 +536,13 @@
 	     */
 
 	    *chPtr = (((byte & 0x0F) << 12)
 		    | ((src[1] & 0x3F) << 6) | (src[2] & 0x3F));
 	    if (*chPtr > 0x7FF) {
+		if ((*chPtr & 0xF800) == 0xD800) {
+		    *chPtr = 0xFFFD;
+		}
 		return 3;
 	    }
 	}
 
 	/*
@@ -964,22 +908,20 @@
 
 const char *
 Tcl_UtfNext(
     const char *src)		/* The current location in the string. */
 {
-    int left;
-    const char *next;
+    int left = totalBytes[UCHAR(*src)];
+    const char *next = src + 1;
 
     if (((*src) & 0xC0) == 0x80) {
 	if ((((*++src) & 0xC0) == 0x80) && (((*++src) & 0xC0) == 0x80)) {
 	    ++src;
 	}
 	return src;
     }
 
-    left = totalBytes[UCHAR(*src)];
-    next = src + 1;
     while (--left) {
 	if ((*next & 0xC0) != 0x80) {
 	    /*
 	     * src points to non-trail byte; We ran out of trail bytes
 	     * before the needs of the lead byte were satisfied.
@@ -987,20 +929,10 @@
 	     */
 	    return src + 1;
 	}
 	next++;
     }
-    /*
-     * Call Invalid() here only if required conditions are met:
-     *    src[0] is known a lead byte.
-     *    src[1] is known a trail byte.
-     * Especially important to prevent calls when src[0] == '\xF8' or '\xFC'
-     * See tests utf-6.37 through utf-6.43 through valgrind or similar tool.
-     */
-    if ((next == src + 1) || Invalid(src)) {
-	return src + 1;
-    }
     return next;
 }
 
 /*
  *---------------------------------------------------------------------------
@@ -1023,103 +955,36 @@
  *---------------------------------------------------------------------------
  */
 
 const char *
 Tcl_UtfPrev(
-    const char *src,		/* A location in a UTF-8 string. */
-    const char *start)		/* Pointer to the beginning of the string */
-{
-    int trailBytesSeen = 0;	/* How many trail bytes have been verified? */
-    const char *fallback = src - 1;
-				/* If we cannot find a lead byte that might
-				 * start a prefix of a valid UTF byte sequence,
-				 * we will fallback to a one-byte back step */
-    const char *look = fallback;
-				/* Start search at the fallback position */
-
-    /* Quick boundary case exit. */
-    if (fallback <= start) {
-	return start;
-    }
-
-    do {
-	unsigned char byte = UCHAR(look[0]);
-
-	if (byte < 0x80) {
-	    /*
-	     * Single byte character. Either this is a correct previous
-	     * character, or it is followed by at least one trail byte
-	     * which indicates a malformed sequence. In either case the
-	     * correct result is to return the fallback.
-	     */
-	    return fallback;
-	}
-	if (byte >= 0xC0) {
-	    /* Non-trail byte; May be multibyte lead. */
-
-	    if ((trailBytesSeen == 0)
-		/*
-		 * We've seen no trailing context to use to check
-		 * anything. From what we know, this non-trail byte
-		 * is a prefix of a previous character, and accepting
-		 * it (the fallback) is correct.
-		 */
-
-		    || (trailBytesSeen >= complete[byte])) {
-		/*
-		 * That is, (1 + trailBytesSeen > needed).
-		 * We've examined more bytes than needed to complete
-		 * this lead byte. No matter about well-formedness or
-		 * validity, the sequence starting with this lead byte
-		 * will never include the fallback location, so we must
-		 * return the fallback location. See test utf-7.17
-		 */
-		return fallback;
-	    }
-
-	    /*
-	     * trailBytesSeen > 0, so we can examine look[1] safely.
-	     * Use that capability to screen out invalid sequences.
-	     */
-
-	    if (Invalid(look)) {
-		/* Reject */
-		return fallback;
-	    }
-	    return (const char *)look;
-	}
-
-	/* We saw a trail byte. */
-	trailBytesSeen++;
-
-	if ((const char *)look == start) {
-	    /*
-	     * Do not read before the start of the string
-	     *
-	     * If we get here, we've examined bytes at every location
-	     * >= start and < src and all of them are trail bytes,
-	     * including (*start).  We need to return our fallback
-	     * and exit this loop before we run past the start of the string.
-	     */
-	    return fallback;
-	}
-
-	/* Continue the search backwards... */
+    const char *src,		/* The current location in the string. */
+    const char *start)		/* Pointer to the beginning of the string, to
+				 * avoid going backwards too far. */
+{
+    const char *look;
+    int i, byte;
+
+    look = --src;
+    for (i = 0; i < 4; i++) {
+	if (look < start) {
+	    if (src < start) {
+		src = start;
+	    }
+	    break;
+	}
+	byte = UCHAR(*look);
+	if ((byte & 0xC0) != 0x80) {
+	    if (look + totalBytes[UCHAR(byte)] < src) {
+		src = look + totalBytes[UCHAR(byte)];
+		break;
+	    }
+	    return look + ((i > 0) && (totalBytes[UCHAR(byte)] == 1));
+	}
 	look--;
-    } while (trailBytesSeen < TCL_UTF_MAX);
-
-    /*
-     * We've seen TCL_UTF_MAX trail bytes, so we know there will not be a
-     * properly formed byte sequence to find, and we can stop looking,
-     * accepting the fallback (for TCL_UTF_MAX > 3) or just go back as
-     * far as we can.
-     */
-#if TCL_UTF_MAX > 3
-    return fallback;
-#else
-    return src - TCL_UTF_MAX;
-#endif
+    }
+    return src;
 }
 
 /*
  *---------------------------------------------------------------------------
  *

Index: tests/encoding.test
==================================================================
--- tests/encoding.test
+++ tests/encoding.test
@@ -36,11 +36,12 @@
 testConstraint testencoding [llength [info commands testencoding]]
 testConstraint testbytestring [llength [info commands testbytestring]]
 testConstraint teststringbytes [llength [info commands teststringbytes]]
 testConstraint exec [llength [info commands exec]]
 testConstraint testgetencpath [llength [info commands testgetencpath]]
-
+testConstraint tip389 [expr {[string length [format %c 0x10000]] eq 2}]
+
 # TclInitEncodingSubsystem is tested by the rest of this file
 # TclFinalizeEncodingSubsystem is not currently tested
 
 test encoding-1.1 {Tcl_GetEncoding: system encoding} -setup {
     set old [encoding system]
@@ -323,76 +324,76 @@
 } c080
 test encoding-15.4 {UtfToUtfProc emoji character input} -body {
     set x \xED\xA0\xBD\xED\xB8\x82
     set y [encoding convertfrom utf-8 \xED\xA0\xBD\xED\xB8\x82]
     list [string length $x] $y
-} -result "6 \U1F602"
+} -result "6 \uFFFD\uFFFD"
 test encoding-15.5 {UtfToUtfProc emoji character input} {
     set x \xF0\x9F\x98\x82
     set y [encoding convertfrom utf-8 \xF0\x9F\x98\x82]
     list [string length $x] $y
 } "4 \U1F602"
-test encoding-15.6 {UtfToUtfProc emoji character output} {
+test encoding-15.6 {UtfToUtfProc emoji character output} tip389 {
     set x \uDE02\uD83D\uDE02\uD83D
     set y [encoding convertto utf-8 \uDE02\uD83D\uDE02\uD83D]
     binary scan $y H* z
     list [string length $y] $z
-} {10 edb882f09f9882eda0bd}
+} {10 efbfbdf09f9882efbfbd}
 test encoding-15.7 {UtfToUtfProc emoji character output} {
     set x \uDE02\uD83D\uD83D
     set y [encoding convertto utf-8 \uDE02\uD83D\uD83D]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {3 9 edb882eda0bdeda0bd}
+} {3 9 efbfbdefbfbdefbfbd}
 test encoding-15.8 {UtfToUtfProc emoji character output} {
     set x \uDE02\uD83D\xE9
     set y [encoding convertto utf-8 \uDE02\uD83D\xE9]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {3 8 edb882eda0bdc3a9}
+} {3 8 efbfbdefbfbdc3a9}
 test encoding-15.9 {UtfToUtfProc emoji character output} {
     set x \uDE02\uD83DX
     set y [encoding convertto utf-8 \uDE02\uD83DX]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {3 7 edb882eda0bd58}
+} {3 7 efbfbdefbfbd58}
 test encoding-15.10 {UtfToUtfProc high surrogate character output} {
     set x \uDE02\xE9
     set y [encoding convertto utf-8 \uDE02\xE9]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {2 5 edb882c3a9}
+} {2 5 efbfbdc3a9}
 test encoding-15.11 {UtfToUtfProc low surrogate character output} {
     set x \uDA02\xE9
     set y [encoding convertto utf-8 \uDA02\xE9]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {2 5 eda882c3a9}
+} {2 5 efbfbdc3a9}
 test encoding-15.12 {UtfToUtfProc high surrogate character output} {
     set x \uDE02Y
     set y [encoding convertto utf-8 \uDE02Y]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {2 4 edb88259}
+} {2 4 efbfbd59}
 test encoding-15.13 {UtfToUtfProc low surrogate character output} {
     set x \uDA02Y
     set y [encoding convertto utf-8 \uDA02Y]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {2 4 eda88259}
+} {2 4 efbfbd59}
 test encoding-15.14 {UtfToUtfProc high surrogate character output} {
     set x \uDE02
     set y [encoding convertto utf-8 \uDE02]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {1 3 edb882}
+} {1 3 efbfbd}
 test encoding-15.15 {UtfToUtfProc low surrogate character output} {
     set x \uDA02
     set y [encoding convertto utf-8 \uDA02]
     binary scan $y H* z
     list [string length $x] [string length $y] $z
-} {1 3 eda882}
+} {1 3 efbfbd}
 test encoding-15.16 {UtfToUtfProc: Invalid 4-byte UTF-8, see [ed29806ba]} {
     set x \xF0\xA0\xA1\xC2
     set y [encoding convertfrom utf-8 \xF0\xA0\xA1\xC2]
     list [string length $x] $y
 } "4 \xF0\xA0\xA1\xC2"
@@ -410,13 +411,13 @@
 test encoding-16.2 {Utf16ToUtfProc} -body {
     set val [encoding convertfrom utf-16 "\xD8\xD8\xDC\xDC"]
     list $val [format %x [scan $val %c]]
 } -result "\U460DC 460dc"
 test encoding-16.3 {Utf16ToUtfProc} -body {
-    set val [encoding convertfrom utf-16 "\xDC\xDC"]
+    set val [encoding convertfrom utf-16 "\xD4\xD4"]
     list $val [format %x [scan $val %c]]
-} -result "\uDCDC dcdc"
+} -result "\uD4D4 d4d4"
 test encoding-16.4 {Ucs2ToUtfProc} -body {
     set val [encoding convertfrom ucs-2 NN]
     list $val [format %x [scan $val %c]]
 } -result "\u4E4E 4e4e"
 test encoding-16.4 {Ucs2ToUtfProc} -body {
@@ -426,15 +427,15 @@
 
 test encoding-17.1 {UtfToUtf16Proc} -body {
     encoding convertto utf-16 "\U460DC"
 } -result "\xD8\xD8\xDC\xDC"
 test encoding-17.2 {UtfToUtf16Proc} -body {
-    encoding convertto utf-16 "\uDCDC"
-} -result "\xDC\xDC"
+    encoding convertto utf-16 "\uD4D4"
+} -result "\xD4\xD4"
 test encoding-17.3 {UtfToUtf16Proc} -body {
-    encoding convertto utf-16 "\uD8D8"
-} -result "\xD8\xD8"
+    encoding convertto utf-16 "\uD0D0"
+} -result "\xD0\xD0"
 test encoding-17.4 {UtfToUcs2Proc} -body {
     encoding convertfrom utf-16 [encoding convertto ucs-2 "\U460DC"]
 } -result "\uFFFD"
 
 test encoding-18.1 {TableToUtfProc} {

Index: tests/utf.test
==================================================================
--- tests/utf.test
+++ tests/utf.test
@@ -19,11 +19,10 @@
 testConstraint ucs2 [expr {[format %c 0x010000] eq "\uFFFD"}]
 testConstraint fullutf [expr {[format %c 0x010000] ne "\uFFFD"}]
 testConstraint utf16 [expr {[string length [format %c 0x10000]] == 2}]
 testConstraint ucs4 [expr {[testConstraint fullutf]
 		&& [string length [format %c 0x10000]] == 1}]
-testConstraint ucs2_utf16 [expr {![testConstraint ucs4]}]
 
 testConstraint Uesc [expr {"\U0041" eq "A"}]
 testConstraint pre388 [expr {"\x741" eq "A"}]
 testConstraint pairsTo4bytes [expr {[llength [info commands teststringbytes]]
 		&& [string length [teststringbytes \uD83D\uDCA9]] == 4}]
@@ -51,26 +50,26 @@
 } 1
 test utf-1.4 {Tcl_UniCharToUtf: 3 byte sequences} testbytestring {
     expr {"\u4E4E" eq [testbytestring \xE4\xB9\x8E]}
 } 1
 test utf-1.5 {Tcl_UniCharToUtf: overflowed Tcl_UniChar} testbytestring {
-    expr {[format %c 0x110000] eq [testbytestring \xEF\xBF\xBD]}
+    expr {[format %c 0x110000] eq "\uFFFD"}
 } 1
 test utf-1.6 {Tcl_UniCharToUtf: negative Tcl_UniChar} testbytestring {
-    expr {[format %c -1] eq [testbytestring \xEF\xBF\xBD]}
+    expr {[format %c -1] eq "\uFFFD"}
 } 1
 test utf-1.7.0 {Tcl_UniCharToUtf: 4 byte sequences} {fullutf Uesc testbytestring} {
     expr {"\U014E4E" eq [testbytestring \xF0\x94\xB9\x8E]}
 } 1
 test utf-1.7.1 {Tcl_UniCharToUtf: 4 byte sequences} {ucs2 Uesc testbytestring} {
     expr {"\U014E4E" eq [testbytestring \xF0\x94\xB9\x8E]}
 } 0
 test utf-1.8 {Tcl_UniCharToUtf: 3 byte sequence, high surrogate} testbytestring {
-    expr {"\uD842" eq [testbytestring \xED\xA1\x82]}
+    expr {"\uD842" eq "\uFFFD"}
 } 1
 test utf-1.9 {Tcl_UniCharToUtf: 3 byte sequence, low surrogate} testbytestring {
-    expr {"\uDC42" eq [testbytestring \xED\xB1\x82]}
+    expr {"\uDC42" eq "\uFFFD"}
 } 1
 test utf-1.10 {Tcl_UniCharToUtf: 3 byte sequence, high surrogate} testbytestring {
     expr {[format %c 0xD842] eq [testbytestring \xED\xA1\x82]}
 } 1
 test utf-1.11 {Tcl_UniCharToUtf: 3 byte sequence, low surrogate} testbytestring {
@@ -78,12 +77,12 @@
 } 1
 test utf-1.12 {Tcl_UniCharToUtf: 4 byte sequence, high/low surrogate} {pairsTo4bytes testbytestring} {
     expr {"\uD842\uDC42" eq [testbytestring \xF0\xA0\xA1\x82]}
 } 1
 test utf-1.13 {Tcl_UniCharToUtf: Invalid surrogate} {Uesc testbytestring} {
-    expr {"\UD842" eq [testbytestring \xEF\xBF\xBD]}
-} 1
+    expr {"\uD842" eq "\uFFFD"}
+    } 1
 
 test utf-2.1 {Tcl_UtfToUniChar: low ascii} {
     string length "abc"
 } 3
 test utf-2.2 {Tcl_UtfToUniChar: naked trail bytes} testbytestring {
@@ -102,22 +101,28 @@
     string length [testbytestring \xE2\xA2]
 } 2
 test utf-2.7 {Tcl_UtfToUniChar: lead (3-byte) followed by 2 trail} testbytestring {
     string length [testbytestring \xE4\xB9\x8E]
 } 1
-test utf-2.8.0 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail} {testbytestring ucs2_utf16} {
+test utf-2.8.0 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail} {testbytestring ucs2} {
     string length [testbytestring \xF0\x90\x80\x80]
-} 2
+} 4
 test utf-2.8.1 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail} {testbytestring ucs4} {
     string length [testbytestring \xF0\x90\x80\x80]
 } 1
+test utf-2.8.2 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail} {testbytestring utf16} {
+    string length [testbytestring \xF0\x90\x80\x80]
+} 2
 test utf-2.9.0 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail} {testbytestring ucs2} {
     string length [testbytestring \xF4\x8F\xBF\xBF]
-} 2
+} 4
 test utf-2.9.1 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail} {Uesc ucs4} {
     string length \U10FFFF
 } 1
+test utf-2.9.2 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail} utf16 {
+    string length \uDBFF\uDFFF
+} 2
 test utf-2.10 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail, underflow} testbytestring {
     string length [testbytestring \xF0\x8F\xBF\xBF]
 } 4
 test utf-2.11 {Tcl_UtfToUniChar: lead (4-byte) followed by 3 trail, overflow} testbytestring {
     # Would decode to U+110000 but that is outside the Unicode range.
@@ -143,11 +148,11 @@
     testnumutfchars \x00
 } 1
 test utf-4.5 {Tcl_NumUtfChars: zero length, calc len} testnumutfchars {
     testnumutfchars "" 0
 } 0
-test utf-4.6 {Tcl_NumUtfChars: length 1, calc len} {testnumutfchars testbytestring} {
+test utf-4.6 {Tcl_NumUtfChars: length 1, calc len} testnumutfchars {
     testnumutfchars \xA2 end
 } 1
 test utf-4.7 {Tcl_NumUtfChars: long string, calc len} {testnumutfchars testbytestring} {
     testnumutfchars abc\xA2[testbytestring \xE4\xB9\x8E\xA2\x4E] end
 } 7
@@ -164,14 +169,17 @@
 test utf-4.11 {Tcl_NumUtfChars: 3 bytes of 4-byte UTF-8 characater} {testnumutfchars testbytestring} {
     testnumutfchars [testbytestring \xF0\x9F\x92\xA9] end-1
 } 3
 test utf-4.12.0 {Tcl_NumUtfChars: #4-byte UTF-8 character} {testnumutfchars testbytestring ucs2} {
     testnumutfchars [testbytestring \xF0\x9F\x92\xA9] end
-} 2
+} 4
 test utf-4.12.1 {Tcl_NumUtfChars: #4-byte UTF-8 character} {testnumutfchars testbytestring ucs4} {
     testnumutfchars [testbytestring \xF0\x9F\x92\xA9] end
 } 1
+test utf-4.12.2 {Tcl_NumUtfChars: #4-byte UTF-8 character} {testnumutfchars testbytestring utf16} {
+    testnumutfchars [testbytestring \xF0\x9F\x92\xA9] end
+} 2
 test utf-4.13 {Tcl_NumUtfChars: end of string} {testnumutfchars testbytestring} {
     testnumutfchars foobar[testbytestring \xF2\xC2\xA0] end
 } 8
 test utf-4.14 {Tcl_NumUtfChars: 3 bytes of 4-byte UTF-8 characater} {testnumutfchars testbytestring} {
     testnumutfchars [testbytestring \xF4\x90\x80\x80] end-1
@@ -394,11 +402,11 @@
     testutfnext \u8820[testbytestring \xF8]
 } 3
 test utf-6.68 {Tcl_UtfNext} {testutfnext testbytestring} {
     testutfnext [testbytestring \xF2\xA0\xA0]G
 } 1
-test utf-6.69.0 {Tcl_UtfNext} {testutfnext testbytestring ucs2_utf16} {
+test utf-6.69.0 {Tcl_UtfNext} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0]
 } 1
 test utf-6.69.1 {Tcl_UtfNext} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0]
 } 4
@@ -412,41 +420,41 @@
     testutfnext [testbytestring \xF2\xA0\xA0\xF2]
 } 1
 test utf-6.73 {Tcl_UtfNext} {testutfnext testbytestring} {
     testutfnext [testbytestring \xF2\xA0\xA0\xF8]
 } 1
-test utf-6.74.0 {Tcl_UtfNext} {testutfnext testbytestring ucs2_utf16} {
+test utf-6.74.0 {Tcl_UtfNext} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0]G
 } 1
 test utf-6.74.1 {Tcl_UtfNext} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0]G
 } 4
-test utf-6.75.0 {Tcl_UtfNext} {testutfnext testbytestring ucs2_utf16} {
+test utf-6.75.0 {Tcl_UtfNext} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xA0]
 } 1
 test utf-6.75.1 {Tcl_UtfNext} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xA0]
 } 4
-test utf-6.76.0 {Tcl_UtfNext} {testutfnext testbytestring ucs2_utf16} {
+test utf-6.76.0 {Tcl_UtfNext} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xD0]
 } 1
 test utf-6.76.1 {Tcl_UtfNext} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xD0]
 } 4
-test utf-6.77.0 {Tcl_UtfNext} {testutfnext testbytestring ucs2_utf16} {
+test utf-6.77.0 {Tcl_UtfNext} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xE8]
 } 1
 test utf-6.77.1 {Tcl_UtfNext} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xE8]
 } 4
-test utf-6.78.0 {Tcl_UtfNext} {testutfnext testbytestring ucs2_utf16} {
+test utf-6.78.0 {Tcl_UtfNext} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xF2]
 } 1
 test utf-6.78.1 {Tcl_UtfNext} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0\xF2]
 } 4
-test utf-6.79.0 {Tcl_UtfNext} {testutfnext testbytestring ucs2_utf16} {
+test utf-6.79.0 {Tcl_UtfNext} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0G\xF8]
 } 1
 test utf-6.79.1 {Tcl_UtfNext} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF2\xA0\xA0\xA0G\xF8]
 } 4
@@ -453,27 +461,30 @@
 test utf-6.80 {Tcl_UtfNext - overlong sequences} testutfnext {
     testutfnext \x00
 } 2
 test utf-6.81 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring} {
     testutfnext [testbytestring \xC0\x81]
-} 1
+} 2
 test utf-6.82 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring} {
     testutfnext [testbytestring \xC1\x80]
-} 1
+} 2
 test utf-6.83 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring} {
     testutfnext [testbytestring \xC2\x80]
 } 2
 test utf-6.84 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring} {
     testutfnext [testbytestring \xE0\x80\x80]
-} 1
+} 3
 test utf-6.85 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring} {
     testutfnext [testbytestring \xE0\xA0\x80]
 } 3
-test utf-6.86 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring} {
+test utf-6.86.0 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring utf16} {
+    testutfnext [testbytestring \xF0\x80\x80\x80]
+} 1
+test utf-6.86.1 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF0\x80\x80\x80]
-} 1
-test utf-6.87.0 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring ucs2_utf16} {
+} 4
+test utf-6.87.0 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring utf16} {
     testutfnext [testbytestring \xF0\x90\x80\x80]
 } 1
 test utf-6.87.1 {Tcl_UtfNext - overlong sequences} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF0\x90\x80\x80]
 } 4
@@ -481,19 +492,22 @@
     testutfnext [testbytestring \xA0\xA0\x00]
 } 2
 test utf-6.89 {Tcl_UtfNext, pointing to 2th byte of 3-byte invalid sequence} {testutfnext testbytestring} {
     testutfnext [testbytestring \x80\x80\x00]
 } 2
-test utf-6.90.0 {Tcl_UtfNext, validity check [493dccc2de]} {testutfnext testbytestring ucs2_utf16} {
-    testutfnext [testbytestring \xF4\x8F\xBF\xBF]
+test utf-6.90.0 {Tcl_UtfNext, validity check [493dccc2de]} {testutfnext utf16} {
+    testutfnext \uDBFF\uDFFF
 } 1
-test utf-6.90.1 {Tcl_UtfNext, validity check [493dccc2de]} {testutfnext testbytestring ucs4} {
-    testutfnext [testbytestring \xF4\x8F\xBF\xBF]
+test utf-6.90.1 {Tcl_UtfNext, validity check [493dccc2de]} {testutfnext ucs4} {
+    testutfnext \U10FFFF
 } 4
-test utf-6.91 {Tcl_UtfNext, validity check [493dccc2de]} {testutfnext testbytestring} {
+test utf-6.91.0 {Tcl_UtfNext, validity check [493dccc2de]} {testutfnext testbytestring utf16} {
+    testutfnext [testbytestring \xF4\x90\x80\x80]
+} 1
+test utf-6.91.1 {Tcl_UtfNext, validity check [493dccc2de]} {testutfnext testbytestring ucs4} {
     testutfnext [testbytestring \xF4\x90\x80\x80]
-} 1
+} 4
 test utf-6.92 {Tcl_UtfNext, pointing to 2th byte of 4-byte valid sequence} {testutfnext testbytestring} {
     testutfnext [testbytestring \xA0\xA0\xA0]
 } 3
 test utf-6.93 {Tcl_UtfNext, pointing to 2th byte of 4-byte invalid sequence} {testutfnext testbytestring} {
     testutfnext [testbytestring \x80\x80\x80]
@@ -566,26 +580,26 @@
     testutfprev A[testbytestring \xF8\xA0\xA0\xA0] 3
 } 2
 test utf-7.9.2 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF8\xA0\xF8\xA0] 3
 } 2
-test utf-7.10.0 {Tcl_UtfPrev} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF2\xA0]
-} 2
-test utf-7.10.1 {Tcl_UtfPrev} {testutfprev testbytestring fullutf} {
-    testutfprev A[testbytestring \xF2\xA0]
-} 1
-test utf-7.10.2 {Tcl_UtfPrev} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 3
-} 2
-test utf-7.10.3 {Tcl_UtfPrev} {testutfprev testbytestring fullutf} {
-    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 3
-} 1
-test utf-7.10.4 {Tcl_UtfPrev} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF2\xA0\xF8\xA0] 3
-} 2
-test utf-7.10.5 {Tcl_UtfPrev} {testutfprev testbytestring fullutf} {
+test utf-7.10.0 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF2\xA0]
+} 2
+test utf-7.10.1 {Tcl_UtfPrev} {testutfprev testbytestring ucs4} {
+    testutfprev A[testbytestring \xF2\xA0]
+} 1
+test utf-7.10.2 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 3
+} 2
+test utf-7.10.3 {Tcl_UtfPrev} {testutfprev testbytestring ucs4} {
+    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 3
+} 1
+test utf-7.10.4 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF2\xA0\xF8\xA0] 3
+} 2
+test utf-7.10.5 {Tcl_UtfPrev} {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF2\xA0\xF8\xA0] 3
 } 1
 test utf-7.11 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE8\xA0]
 } 1
@@ -607,42 +621,42 @@
 test utf-7.12.2 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xD0\xA0\xF8\xA0] 3
 } 1
 test utf-7.13 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xA0\xA0]
-} 2
+} 1
 test utf-7.13.1 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xA0\xA0\xA0\xA0] 3
-} 2
+} 1
 test utf-7.13.2 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xA0\xA0\xF8\xA0] 3
-} 2
+} 1
 test utf-7.14 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF8\xA0\xA0]
-} 3
+} 2
 test utf-7.14.1 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF8\xA0\xA0\xA0] 4
-} 3
+} 2
 test utf-7.14.2 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF8\xA0\xA0\xF8] 4
-} 3
-test utf-7.15.0 {Tcl_UtfPrev} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF2\xA0\xA0]
-} 3
-test utf-7.15.1 {Tcl_UtfPrev} {testutfprev testbytestring fullutf} {
-    testutfprev A[testbytestring \xF2\xA0\xA0]
-} 1
-test utf-7.15.2 {Tcl_UtfPrev} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 4
-} 3
-test utf-7.15.3 {Tcl_UtfPrev} {testutfprev testbytestring fullutf} {
-    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 4
-} 1
-test utf-7.15.4 {Tcl_UtfPrev} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF2\xA0\xA0\xF8] 4
-} 3
-test utf-7.15.5 {Tcl_UtfPrev} {testutfprev testbytestring fullutf} {
+} 2
+test utf-7.15.0 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF2\xA0\xA0]
+} 2
+test utf-7.15.1 {Tcl_UtfPrev} {testutfprev testbytestring ucs4} {
+    testutfprev A[testbytestring \xF2\xA0\xA0]
+} 1
+test utf-7.15.2 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 4
+} 2
+test utf-7.15.3 {Tcl_UtfPrev} {testutfprev testbytestring ucs4} {
+    testutfprev A[testbytestring \xF2\xA0\xA0\xA0] 4
+} 1
+test utf-7.15.4 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF2\xA0\xA0\xF8] 4
+} 2
+test utf-7.15.5 {Tcl_UtfPrev} {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF2\xA0\xA0\xF8] 4
 } 1
 test utf-7.16 {Tcl_UtfPrev} testutfprev {
     testutfprev A\u8820
 } 1
@@ -652,80 +666,92 @@
 test utf-7.16.2 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A\u8820[testbytestring \xF8] 4
 } 1
 test utf-7.17 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xD0\xA0\xA0]
-} 3
+} 1
 test utf-7.17.1 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xD0\xA0\xA0\xA0] 4
-} 3
+} 1
 test utf-7.17.2 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xD0\xA0\xA0\xF8] 4
-} 3
-test utf-7.18.0 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+} 1
+test utf-7.18.0 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xA0\xA0\xA0]
 } 1
-test utf-7.18.1 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+test utf-7.18.1 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xA0\xA0\xA0\xA0] 4
 } 1
-test utf-7.18.2 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+test utf-7.18.2 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xA0\xA0\xA0\xF8] 4
 } 1
-test utf-7.19 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+test utf-7.19 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF8\xA0\xA0\xA0]
 } 2
-test utf-7.20 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+test utf-7.20.0 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF2\xA0\xA0\xA0]
+} 2
+test utf-7.20.1 {Tcl_UtfPrev} {testutfprev testbytestring ucs2} {
     testutfprev A[testbytestring \xF2\xA0\xA0\xA0]
-} 2
-test utf-7.21 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+} 1
+test utf-7.21 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A\u8820[testbytestring \xA0]
-} 2
-test utf-7.22 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+} 1
+test utf-7.22 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xD0\xA0\xA0\xA0]
-} 2
-test utf-7.23 {Tcl_UtfPrev} {testutfprev testbytestring utf16} {
+} 3
+test utf-7.23 {Tcl_UtfPrev} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xA0\xA0\xA0\xA0]
-} 2
+} 4
 test utf-7.24 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xC0\x81]
-} 2
+} 1
 test utf-7.25 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xC0\x81] 2
 } 1
 test utf-7.26 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE0\x80\x80]
-} 3
+} 1
 test utf-7.27 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE0\x80]
-} 2
+} 1
 test utf-7.27.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE0\x80\x80] 3
-} 2
+} 1
 test utf-7.28 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE0]
 } 1
 test utf-7.28.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE0\x80\x80] 2
 } 1
-test utf-7.29 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
+test utf-7.29.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF0\x80\x80\x80]
+} 2
+test utf-7.29.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF0\x80\x80\x80]
+} 1
+test utf-7.30.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF0\x80\x80\x80] 4
 } 2
-test utf-7.30 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
+test utf-7.30.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF0\x80\x80\x80] 4
-} 3
-test utf-7.31 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
+} 1
+test utf-7.31.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF0\x80\x80\x80] 3
+} 2
+test utf-7.31.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF0\x80\x80\x80] 3
-} 2
+} 1
 test utf-7.32 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF0\x80\x80\x80] 2
 } 1
 test utf-7.33 {Tcl_UtfPrev -- overlong sequence}  testutfprev {
     testutfprev A\x00
 } 1
 test utf-7.34 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xC1\x80]
-} 2
+} 1
 test utf-7.35 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xC2\x80]
 } 1
 test utf-7.36 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE0\xA0\x80]
@@ -734,23 +760,26 @@
     testutfprev A[testbytestring \xE0\xA0\x80] 3
 } 1
 test utf-7.38 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xE0\xA0\x80] 2
 } 1
-test utf-7.39 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
+test utf-7.39.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF0\x90\x80\x80]
+} 2
+test utf-7.39.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF0\x90\x80\x80]
-} 2
-test utf-7.40.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs2} {
+} 1
+test utf-7.40.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
     testutfprev A[testbytestring \xF0\x90\x80\x80] 4
-} 3
-test utf-7.40.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring fullutf} {
+} 2
+test utf-7.40.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF0\x90\x80\x80] 4
 } 1
-test utf-7.41.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs2} {
+test utf-7.41.0 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring utf16} {
     testutfprev A[testbytestring \xF0\x90\x80\x80] 3
 } 2
-test utf-7.41.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring fullutf} {
+test utf-7.41.1 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF0\x90\x80\x80] 3
 } 1
 test utf-7.42 {Tcl_UtfPrev -- overlong sequence}  {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF0\x90\x80\x80] 2
 } 1
@@ -761,50 +790,65 @@
     testutfprev [testbytestring \xA0\xA0]
 } 1
 test utf-7.45 {Tcl_UtfPrev -- no lead byte at start}  {testutfprev testbytestring} {
     testutfprev [testbytestring \xA0\xA0\xA0]
 } 2
-test utf-7.46 {Tcl_UtfPrev -- no lead byte at start}  {testutfprev testbytestring utf16} {
+test utf-7.46.0 {Tcl_UtfPrev -- no lead byte at start}  {testutfprev testbytestring utf16} {
+    testutfprev [testbytestring \xA0\xA0\xA0\xA0]
+} 3
+test utf-7.46.1 {Tcl_UtfPrev -- no lead byte at start}  {testutfprev testbytestring ucs4} {
     testutfprev [testbytestring \xA0\xA0\xA0\xA0]
-} 1
+} 3
 test utf-7.47 {Tcl_UtfPrev, pointing to 3th byte of 3-byte valid sequence} {testutfprev testbytestring} {
     testutfprev [testbytestring \xE8\xA0]
 } 0
-test utf-7.47.1 {Tcl_UtfPrev, pointing to 3th byte of 3-byte valid sequence} testutfprev {
+test utf-7.47.1 {Tcl_UtfPrev, pointing to 3th byte of 3-byte valid sequence} {testutfprev testbytestring} {
     testutfprev \u8820 2
 } 0
 test utf-7.47.2 {Tcl_UtfPrev, pointing to 3th byte of 3-byte invalid sequence} {testutfprev testbytestring} {
     testutfprev [testbytestring \xE8\xA0\x00] 2
 } 0
 test utf-7.48.0 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring utf16} {
-    testutfprev A[testbytestring \xF4\x8F\xBF\xBF]
-} 2
-test utf-7.48.1 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF4\x8F\xBF\xBF] 4
-} 3
-test utf-7.48.2 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring fullutf} {
-    testutfprev A[testbytestring \xF4\x8F\xBF\xBF] 4
-} 1
-test utf-7.48.3 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs2} {
-    testutfprev A[testbytestring \xF4\x8F\xBF\xBF] 3
-} 2
-test utf-7.48.4 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring fullutf} {
-    testutfprev A[testbytestring \xF4\x8F\xBF\xBF] 3
-} 1
-test utf-7.48.5 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring} {
-    testutfprev A[testbytestring \xF4\x8F\xBF\xBF] 2
+    testutfprev A\uDBFF\uDFFF
+} 2
+test utf-7.48.1 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs4} {
+    testutfprev A\U10FFFF
+} 1
+test utf-7.48.2 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring utf16} {
+    testutfprev A\uDBFF\uDFFF 4
+} 2
+test utf-7.48.3 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs4} {
+    testutfprev A\U10FFFF 4
+} 1
+test utf-7.48.4 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring utf16} {
+    testutfprev A\uDBFF\uDFFF 3
+} 2
+test utf-7.48.5 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs4} {
+    testutfprev A\U10FFFF 3
+} 1
+test utf-7.48.6 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring} {
+    testutfprev A\U10FFFF 2
 } 1
 test utf-7.49.0 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring utf16} {
     testutfprev A[testbytestring \xF4\x90\x80\x80]
 } 2
-test utf-7.49.1 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring} {
+test utf-7.49.1 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs4} {
+    testutfprev A[testbytestring \xF4\x90\x80\x80]
+} 1
+test utf-7.49.2 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring utf16} {
+    testutfprev A[testbytestring \xF4\x90\x80\x80] 4
+} 2
+test utf-7.49.3 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs4} {
     testutfprev A[testbytestring \xF4\x90\x80\x80] 4
-} 3
-test utf-7.49.2 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring} {
+} 1
+test utf-7.49.4 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring utf16} {
     testutfprev A[testbytestring \xF4\x90\x80\x80] 3
 } 2
-test utf-7.49.3 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring} {
+test utf-7.49.5 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring ucs4} {
+    testutfprev A[testbytestring \xF4\x90\x80\x80] 3
+} 1
+test utf-7.49.6 {Tcl_UtfPrev, validity check [493dccc2de]} {testutfprev testbytestring} {
     testutfprev A[testbytestring \xF4\x90\x80\x80] 2
 } 1
 
 test utf-8.1 {Tcl_UniCharAtIndex: index = 0} {
     string index abcd 0
@@ -815,11 +859,11 @@
 test utf-8.3 {Tcl_UniCharAtIndex: index > 0} {
     string index abcd 2
 } c
 test utf-8.4 {Tcl_UniCharAtIndex: index > 0} {
     string index \u4E4E\u25A\xFF\u543 2
-} \xFF
+} \uFF
 test utf-8.5.0 {Tcl_UniCharAtIndex: high surrogate} ucs2 {
     string index \uD842 0
 } \uD842
 test utf-8.5.1 {Tcl_UniCharAtIndex: high surrogate} ucs4 {
     string index \uD842 0
@@ -833,29 +877,29 @@
 test utf-8.7.0 {Tcl_UniCharAtIndex: Emoji} ucs2 {
     string index \uD83D\uDE00G 0
 } \uD83D
 test utf-8.7.1 {Tcl_UniCharAtIndex: Emoji} ucs4 {
     string index \uD83D\uDE00G 0
-} \U1F600
+} \uFFFD
 test utf-8.7.2 {Tcl_UniCharAtIndex: Emoji} utf16 {
     string index \uD83D\uDE00G 0
 } \U1F600
 test utf-8.8.0 {Tcl_UniCharAtIndex: Emoji} ucs2 {
     string index \uD83D\uDE00G 1
 } \uDE00
 test utf-8.8.1 {Tcl_UniCharAtIndex: Emoji} ucs4 {
     string index \uD83D\uDE00G 1
-} G
+} \uFFFD
 test utf-8.8.2 {Tcl_UniCharAtIndex: Emoji} utf16 {
     string index \uD83D\uDE00G 1
 } {}
 test utf-8.9.0 {Tcl_UniCharAtIndex: Emoji} ucs2 {
     string index \uD83D\uDE00G 2
 } G
 test utf-8.9.1 {Tcl_UniCharAtIndex: Emoji} ucs4 {
     string index \uD83D\uDE00G 2
-} {}
+} G
 test utf-8.9.2 {Tcl_UniCharAtIndex: Emoji} utf16 {
     string index \uD83D\uDE00G 2
 } G
 test utf-8.10.0 {Tcl_UniCharAtIndex: Emoji} {Uesc ucs2} {
     string index \U1F600G 0
@@ -894,29 +938,29 @@
 test utf-9.3.0 {Tcl_UtfAtIndex: index = 0, Emoji} ucs2 {
     string range \uD83D\uDE00G 0 0
 } \uD83D
 test utf-9.3.1 {Tcl_UtfAtIndex: index = 0, Emoji} ucs4 {
     string range \uD83D\uDE00G 0 0
-} \U1F600
+} \uFFFD
 test utf-9.3.2 {Tcl_UtfAtIndex: index = 0, Emoji} utf16 {
     string range \uD83D\uDE00G 0 0
 } \U1F600
 test utf-9.4.0 {Tcl_UtfAtIndex: index > 0, Emoji} ucs2 {
     string range \uD83D\uDE00G 1 1
 } \uDE00
 test utf-9.4.1 {Tcl_UtfAtIndex: index > 0, Emoji} ucs4 {
     string range \uD83D\uDE00G 1 1
-} G
+} \uFFFD
 test utf-9.4.2 {Tcl_UtfAtIndex: index > 0, Emoji} utf16 {
     string range \uD83D\uDE00G 1 1
 } {}
 test utf-9.5.0 {Tcl_UtfAtIndex: index > 0, Emoji} ucs2 {
     string range \uD83D\uDE00G 2 2
 } G
 test utf-9.5.1 {Tcl_UtfAtIndex: index > 0, Emoji} ucs4 {
     string range \uD83D\uDE00G 2 2
-} {}
+} G
 test utf-9.5.2 {Tcl_UtfAtIndex: index > 0, Emoji} utf16 {
     string range \uD83D\uDE00G 2 2
 } G
 test utf-9.6.0 {Tcl_UtfAtIndex: index = 0, Emoji} {Uesc ucs2} {
     string range \U1f600G 0 0
@@ -1304,20 +1348,11 @@
 UniCharCaseCmpTest < \uFFFF \U10000		{Uesc ucs4}
 UniCharCaseCmpTest > [format %c 0x10000] \uFFFF	ucs4
 UniCharCaseCmpTest > \U10000 \uFFFF		{Uesc ucs4}
 
 
-test utf-26.1 {Tcl_UniCharDString} -setup {
-    testobj freeallvars
-} -constraints {teststringobj testbytestring} -cleanup {
-    testobj freeallvars
-} -body {
-    teststringobj set 1 foo
-    teststringobj maxchars 1
-    teststringobj append 1 [testbytestring barsoom\xF2\xC2\x80] 10
-    scan [string index [teststringobj get 1] 11] %c
-} -result 128
+
 
 
 unset count
 rename UniCharCaseCmpTest {}