diff --git a/config.nims b/config.nims
index 08448f8..d440a34 100644
--- a/config.nims
+++ b/config.nims
@@ -38,6 +38,11 @@ task quickstartTests, "Run quickstart tests":
   --verbosity:0
   setCommand "c", "test/tquickstart"
 
+task hintsTests, "Run hints tests":
+  --r
+  --verbosity:0
+  setCommand "c", "test/thints"
+
 task documentation, "Generate documentation":
   exec "mkdir -p docout"
   withDir "doc":
diff --git a/test/tests.nim b/test/tests.nim
index e58fbc9..b19ca56 100644
--- a/test/tests.nim
+++ b/test/tests.nim
@@ -5,7 +5,7 @@
 #    distribution, for details about the copyright.
 
 {.warning[UnusedImport]: off.}
-import tlex, tjson, tserialization, tparser, tquickstart, tannotations
+import tlex, tjson, tserialization, tparser, tquickstart, tannotations, thints
 
 when not defined(gcArc) or defined(gcOrc):
-  import tdom
\ No newline at end of file
+  import tdom
diff --git a/test/thints.nim b/test/thints.nim
new file mode 100644
index 0000000..a249c80
--- /dev/null
+++ b/test/thints.nim
@@ -0,0 +1,262 @@
+import unittest
+import ../yaml/hints
+
+suite "Hints":
+  test "Int":
+    # [-+]? [0-9]+
+    assert guessType("0") == yTypeInteger
+    assert guessType("01") == yTypeInteger
+    assert guessType("10") == yTypeInteger
+    assert guessType("248") == yTypeInteger
+    assert guessType("-4248") == yTypeInteger
+    assert guessType("+42489") == yTypeInteger
+
+  test "Non-Int":
+    assert guessType("0+0") != yTypeInteger
+    assert guessType("0-1") != yTypeInteger
+    assert guessType("1x0") != yTypeInteger
+    assert guessType("248e") != yTypeInteger
+    assert guessType("-4248 4") != yTypeInteger
+    assert guessType("+-4248") != yTypeInteger
+
+  test "Float":
+    # [-+]? ( \. [0-9]+ | [0-9]+ ( \. [0-9]* )? ) ( [eE] [-+]? [0-9]+ )?
+
+    # Batch: [-+]? ( \. [0-9]+ | [0-9]+ ( \. [0-9]* )? )
+    assert guessType(".5") == yTypeFloat
+    assert guessType("+.5") == yTypeFloat
+    assert guessType("-.5") == yTypeFloat
+    assert guessType("0.5") == yTypeFloat
+    assert guessType("+0.5") == yTypeFloat
+    assert guessType("-0.5") == yTypeFloat
+    assert guessType("5.5") == yTypeFloat
+    assert guessType("+5.5") == yTypeFloat
+    assert guessType("-5.5") == yTypeFloat
+    assert guessType("5.") == yTypeFloat
+    assert guessType("+5.") == yTypeFloat
+    assert guessType("-5.") == yTypeFloat
+
+    # Batch: [-+]? \. [0-9]+ [eE] [-+]? [0-9]+
+    assert guessType(".5e5") == yTypeFloat
+    assert guessType("+.5e5") == yTypeFloat
+    assert guessType("-.5e5") == yTypeFloat
+    assert guessType(".5e+5") == yTypeFloat
+    assert guessType("+.5e+5") == yTypeFloat
+    assert guessType("-.5e+5") == yTypeFloat
+    assert guessType(".5e-5") == yTypeFloat
+    assert guessType("+.5e-5") == yTypeFloat
+    assert guessType("-.5e-5") == yTypeFloat
+
+    assert guessType(".5e05") == yTypeFloat
+    assert guessType("+.5e05") == yTypeFloat
+    assert guessType("-.5e05") == yTypeFloat
+    assert guessType(".5e+05") == yTypeFloat
+    assert guessType("+.5e+05") == yTypeFloat
+    assert guessType("-.5e+05") == yTypeFloat
+    assert guessType(".5e-05") == yTypeFloat
+    assert guessType("+.5e-05") == yTypeFloat
+    assert guessType("-.5e-05") == yTypeFloat
+
+    assert guessType(".05e5") == yTypeFloat
+    assert guessType("+.05e5") == yTypeFloat
+    assert guessType("-.05e5") == yTypeFloat
+    assert guessType(".05e+5") == yTypeFloat
+    assert guessType("+.05e+5") == yTypeFloat
+    assert guessType("-.05e+5") == yTypeFloat
+    assert guessType(".05e-5") == yTypeFloat
+    assert guessType("+.05e-5") == yTypeFloat
+    assert guessType("-.05e-5") == yTypeFloat
+
+    assert guessType(".05e05") == yTypeFloat
+    assert guessType("+.05e05") == yTypeFloat
+    assert guessType("-.05e05") == yTypeFloat
+    assert guessType(".05e+05") == yTypeFloat
+    assert guessType("+.05e+05") == yTypeFloat
+    assert guessType("-.05e+05") == yTypeFloat
+    assert guessType(".05e-05") == yTypeFloat
+    assert guessType("+.05e-05") == yTypeFloat
+    assert guessType("-.05e-05") == yTypeFloat
+
+    # Batch: [-+]? [0-9]+ \. [0-9]* [eE] [-+]? [0-9]+
+    assert guessType("0.5e5") == yTypeFloat
+    assert guessType("+0.5e5") == yTypeFloat
+    assert guessType("-0.5e5") == yTypeFloat
+    assert guessType("0.5e+5") == yTypeFloat
+    assert guessType("+0.5e+5") == yTypeFloat
+    assert guessType("-0.5e+5") == yTypeFloat
+    assert guessType("0.5e-5") == yTypeFloat
+    assert guessType("+0.5e-5") == yTypeFloat
+    assert guessType("-0.5e-5") == yTypeFloat
+
+    assert guessType("0.5e05") == yTypeFloat
+    assert guessType("+0.5e05") == yTypeFloat
+    assert guessType("-0.5e05") == yTypeFloat
+    assert guessType("0.5e+05") == yTypeFloat
+    assert guessType("+0.5e+05") == yTypeFloat
+    assert guessType("-0.5e+05") == yTypeFloat
+    assert guessType("0.5e-05") == yTypeFloat
+    assert guessType("+0.5e-05") == yTypeFloat
+    assert guessType("-0.5e-05") == yTypeFloat
+
+    assert guessType("0.05e5") == yTypeFloat
+    assert guessType("+0.05e5") == yTypeFloat
+    assert guessType("-0.05e5") == yTypeFloat
+    assert guessType("0.05e+5") == yTypeFloat
+    assert guessType("+0.05e+5") == yTypeFloat
+    assert guessType("-0.05e+5") == yTypeFloat
+    assert guessType("0.05e-5") == yTypeFloat
+    assert guessType("+0.05e-5") == yTypeFloat
+    assert guessType("-0.05e-5") == yTypeFloat
+
+    assert guessType("0.05e05") == yTypeFloat
+    assert guessType("+0.05e05") == yTypeFloat
+    assert guessType("-0.05e05") == yTypeFloat
+    assert guessType("0.05e+05") == yTypeFloat
+    assert guessType("+0.05e+05") == yTypeFloat
+    assert guessType("-0.05e+05") == yTypeFloat
+    assert guessType("0.05e-05") == yTypeFloat
+    assert guessType("+0.05e-05") == yTypeFloat
+    assert guessType("-0.05e-05") == yTypeFloat
+
+    # Batch: [-+]? [0-9]+ [eE] [-+]? [0-9]+
+    assert guessType("5e5") == yTypeFloat
+    assert guessType("+5e5") == yTypeFloat
+    assert guessType("-5e5") == yTypeFloat
+    assert guessType("5e+5") == yTypeFloat
+    assert guessType("+5e+5") == yTypeFloat
+    assert guessType("-5e+5") == yTypeFloat
+    assert guessType("5e-5") == yTypeFloat
+    assert guessType("+5e-5") == yTypeFloat
+    assert guessType("-5e-5") == yTypeFloat
+
+    assert guessType("5e05") == yTypeFloat
+    assert guessType("+5e05") == yTypeFloat
+    assert guessType("-5e05") == yTypeFloat
+    assert guessType("5e+05") == yTypeFloat
+    assert guessType("+5e+05") == yTypeFloat
+    assert guessType("-5e+05") == yTypeFloat
+    assert guessType("5e-05") == yTypeFloat
+    assert guessType("+5e-05") == yTypeFloat
+    assert guessType("-5e-05") == yTypeFloat
+
+    assert guessType("05e5") == yTypeFloat
+    assert guessType("+05e5") == yTypeFloat
+    assert guessType("-05e5") == yTypeFloat
+    assert guessType("05e+5") == yTypeFloat
+    assert guessType("+05e+5") == yTypeFloat
+    assert guessType("-05e+5") == yTypeFloat
+    assert guessType("05e-5") == yTypeFloat
+    assert guessType("+05e-5") == yTypeFloat
+    assert guessType("-05e-5") == yTypeFloat
+
+    assert guessType("05e05") == yTypeFloat
+    assert guessType("+05e05") == yTypeFloat
+    assert guessType("-05e05") == yTypeFloat
+    assert guessType("05e+05") == yTypeFloat
+    assert guessType("+05e+05") == yTypeFloat
+    assert guessType("-05e+05") == yTypeFloat
+    assert guessType("05e-05") == yTypeFloat
+    assert guessType("+05e-05") == yTypeFloat
+    assert guessType("-05e-05") == yTypeFloat
+
+  test "Non-Float":
+    assert guessType(".") != yTypeFloat
+    assert guessType("+.") != yTypeFloat
+    assert guessType("-.") != yTypeFloat
+    assert guessType(".e4") != yTypeFloat
+    assert guessType("+.e4") != yTypeFloat
+    assert guessType("-.e4") != yTypeFloat
+
+  test "Bool-True":
+    # ``true | True | TRUE``
+    assert guessType("true") == yTypeBoolTrue
+    assert guessType("True") == yTypeBoolTrue
+    assert guessType("TRUE") == yTypeBoolTrue
+
+  test "Bool-False":
+    # ``false | False | FALSE``
+    assert guessType("false") == yTypeBoolFalse
+    assert guessType("False") == yTypeBoolFalse
+    assert guessType("FALSE") == yTypeBoolFalse
+
+  test "Non-Bool":
+    # y, yes, on should not be treated as bool
+    assert guessType("y") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("Y") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("yes") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("Yes") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("on") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("On") notin {yTypeBoolTrue, yTypeBoolFalse}
+
+    # n, no, off should not be treated as bool
+    assert guessType("n") notin {yTypeBoolFalse, yTypeBoolFalse}
+    assert guessType("N") notin {yTypeBoolFalse, yTypeBoolFalse}
+    assert guessType("no") notin {yTypeBoolFalse, yTypeBoolFalse}
+    assert guessType("No") notin {yTypeBoolFalse, yTypeBoolFalse}
+    assert guessType("off") notin {yTypeBoolFalse, yTypeBoolFalse}
+    assert guessType("Off") notin {yTypeBoolFalse, yTypeBoolFalse}
+
+    # miss-cased words should not be treated as bool
+    assert guessType("tRUE") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("TRue") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("fAlse") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("FALSe") notin {yTypeBoolTrue, yTypeBoolFalse}
+
+    # miss-spelled words should not be treated as bool
+    assert guessType("ye") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("yse") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("nO") notin {yTypeBoolTrue, yTypeBoolFalse}
+    assert guessType("flase") notin {yTypeBoolTrue, yTypeBoolFalse}
+
+  test "Inf":
+    # ``[-+]? ( \.inf | \.Inf | \.INF )``
+    assert guessType(".inf") == yTypeFloatInf
+    assert guessType(".Inf") == yTypeFloatInf
+    assert guessType(".INF") == yTypeFloatInf
+
+    assert guessType("+.inf") == yTypeFloatInf
+    assert guessType("+.Inf") == yTypeFloatInf
+    assert guessType("+.INF") == yTypeFloatInf
+
+    assert guessType("-.inf") == yTypeFloatInf
+    assert guessType("-.Inf") == yTypeFloatInf
+    assert guessType("-.INF") == yTypeFloatInf
+
+  test "Non-Inf":
+    assert guessType(".InF") != yTypeFloatInf
+    assert guessType(".INf") != yTypeFloatInf
+    assert guessType("inf") != yTypeFloatInf
+    assert guessType("Inf") != yTypeFloatInf
+    assert guessType("INF") != yTypeFloatInf
+
+  test "NaN":
+    # ``\.nan | \.NaN | \.NAN``
+    assert guessType(".nan") == yTypeFloatNaN
+    assert guessType(".NaN") == yTypeFloatNaN
+    assert guessType(".NAN") == yTypeFloatNaN
+
+  test "Non-NaN":
+    assert guessType(".nAn") != yTypeFloatNaN
+    assert guessType(".Nan") != yTypeFloatNaN
+    assert guessType(".nAN") != yTypeFloatNaN
+    assert guessType("nan") != yTypeFloatNaN
+    assert guessType("NaN") != yTypeFloatNaN
+    assert guessType("NAN") != yTypeFloatNaN
+
+  test "Null":
+    # ``null | Null | NULL | ~``
+    assert guessType("null") == yTypeNull
+    assert guessType("Null") == yTypeNull
+    assert guessType("NULL") == yTypeNull
+    assert guessType("~") == yTypeNull
+
+  test "Non-Null":
+    assert guessType("NuLL") != yTypeNull
+    assert guessType("NUll") != yTypeNull
+    assert guessType("NULl") != yTypeNull
+    assert guessType("nULL") != yTypeNull
+    assert guessType("~~") != yTypeNull
+    assert guessType(".null") != yTypeNull
+    assert guessType(".Null") != yTypeNull
+    assert guessType(".NULL") != yTypeNull
+    assert guessType(".~") != yTypeNull
diff --git a/yaml/hints.nim b/yaml/hints.nim
index 26b5159..d75e038 100644
--- a/yaml/hints.nim
+++ b/yaml/hints.nim
@@ -23,16 +23,18 @@ type
     ## You can use it to determine the type of YAML scalars that have a '?'
     ## non-specific tag, but using this feature is completely optional.
     ##
+    ## See also: https://yaml.org/spec/1.2.2/#103-core-schema
+    ##
     ## ================== =========================
     ## Name               RegEx
     ## ================== =========================
-    ## ``yTypeInteger``   ``0 | -? [1-9] [0-9]*``
-    ## ``yTypeFloat``     ``-? [1-9] ( \. [0-9]* [1-9] )? ( e [-+] [1-9] [0-9]* )?``
-    ## ``yTypeFloatInf``  ``-? \. (inf | Inf | INF)``
-    ## ``yTypeFloatNaN``  ``-? \. (nan | NaN | NAN)``
-    ## ``yTypeBoolTrue``  ``y|Y|yes|Yes|YES|true|True|TRUE|on|On|ON``
-    ## ``yTypeBoolFalse`` ``n|N|no|No|NO|false|False|FALSE|off|Off|OFF``
-    ## ``yTypeNull``      ``~ | null | Null | NULL``
+    ## ``yTypeInteger``   ``[-+]? [0-9]+``
+    ## ``yTypeFloat``     ``[-+]? ( \. [0-9]+ | [0-9]+ ( \. [0-9]* )? ) ( [eE] [-+]? [0-9]+ )?``
+    ## ``yTypeFloatInf``  ``[-+]? ( \.inf | \.Inf | \.INF )``
+    ## ``yTypeFloatNaN``  ``\.nan | \.NaN | \.NAN``
+    ## ``yTypeBoolTrue``  ``true | True | TRUE``
+    ## ``yTypeBoolFalse`` ``false | False | FALSE``
+    ## ``yTypeNull``      ``null | Null | NULL | ~``
     ## ``yTypeTimestamp`` see `here <http://yaml.org/type/timestamp.html>`_.
     ## ``yTypeUnknown``   ``*``
     ## ================== =========================
@@ -43,25 +45,19 @@ type
     ythInitial,
     ythF, ythFA, ythFAL, ythFALS, ythFALSE,
     ythN, ythNU, ythNUL, ythNULL,
-          ythNO,
-    ythO, ythON,
-          ythOF, ythOFF,
     ythT, ythTR, ythTRU, ythTRUE,
-    ythY, ythYE, ythYES,
 
     ythPoint, ythPointI, ythPointIN, ythPointINF,
               ythPointN, ythPointNA, ythPointNAN,
 
-    ythLowerFA, ythLowerFAL, ythLowerFALS,
-    ythLowerNU, ythLowerNUL,
-    ythLowerOF,
-    ythLowerTR, ythLowerTRU,
-    ythLowerYE,
+    ythLowerF, ythLowerFA, ythLowerFAL, ythLowerFALS,
+    ythLowerN, ythLowerNU, ythLowerNUL,
+    ythLowerT, ythLowerTR, ythLowerTRU,
 
-    ythPointLowerIN, ythPointLowerN, ythPointLowerNA,
+    ythPointLowerI, ythPointLowerIN,
+    ythPointLowerN, ythPointLowerNA,
 
-    ythMinus, yth0, ythInt1, ythInt1Zero, ythInt2, ythInt2Zero, ythInt3,
-    ythInt3Zero, ythInt4, ythInt4Zero, ythInt,
+    ythMinus, ythPlus, ythInt1, ythInt2, ythInt3, ythInt4, ythInt,
     ythDecimal, ythNumE, ythNumEPlusMinus, ythExponent,
 
     ythYearMinus, ythMonth1, ythMonth2, ythMonthMinus, ythMonthMinusNoYmd,
@@ -111,63 +107,33 @@ template advanceTypeHint(ch: char) {.dirty.} =
   typeHintStateMachine ch:
   of '~': ythInitial => ythNULL
   of '.':
-    [yth0, ythInt1Zero, ythInt1, ythInt2, ythInt3, ythInt4, ythInt] => ythDecimal
-    [ythInitial, ythMinus] => ythPoint
-    ythSecond2             => ythFraction
+    [ythInt1, ythInt2, ythInt3, ythInt4, ythInt] => ythDecimal
+    [ythInitial, ythMinus, ythPlus] => ythPoint
+    ythSecond2                      => ythFraction
   of '+':
-    ythNumE => ythNumEPlusMinus
+    ythInitial                => ythPlus
+    ythNumE                   => ythNumEPlusMinus
     [ythFraction, ythSecond2] => ythAfterTimePlusMinus
   of '-':
     ythInitial                => ythMinus
     ythNumE                   => ythNumEPlusMinus
-    [ythInt4, ythInt4Zero]    => ythYearMinus
+    ythInt4                   => ythYearMinus
     ythMonth1                 => ythMonthMinusNoYmd
     ythMonth2                 => ythMonthMinus
     [ythFraction, ythSecond2] => ythAfterTimePlusMinus
   of '_':
     [ythInt1, ythInt2, ythInt3, ythInt4] => ythInt
-    [ythInt, ythDecimal] => nil
+    [ythInt, ythDecimal]      => nil
   of ':':
     [ythHour1, ythHour2]      => ythHourColon
     ythMinute2                => ythMinuteColon
     [ythTzHour1, ythTzHour2]  => ythTzHourColon
-  of '0':
-    ythInitial                  => ythInt1Zero
-    ythMinus                    => yth0
-    [ythNumE, ythNumEPlusMinus] => ythExponent
-    ythInt1                     => ythInt2
-    ythInt1Zero                 => ythInt2Zero
-    ythInt2                     => ythInt3
-    ythInt2Zero                 => ythInt3Zero
-    ythInt3                     => ythInt4
-    ythInt3Zero                 => ythInt4Zero
-    ythInt4                     => ythInt
-    ythYearMinus                => ythMonth1
-    ythMonth1                   => ythMonth2
-    ythMonthMinus               => ythDay1
-    ythMonthMinusNoYmd          => ythDay1NoYmd
-    ythDay1                     => ythDay2
-    ythDay1NoYmd                => ythDay2NoYmd
-    [ythAfterDaySpace, ythAfterDayT] => ythHour1
-    ythHour1                    => ythHour2
-    ythHourColon                => ythMinute1
-    ythMinute1                  => ythMinute2
-    ythMinuteColon              => ythSecond1
-    ythSecond1                  => ythSecond2
-    ythAfterTimePlusMinus       => ythTzHour1
-    ythTzHour1                  => ythTzHour2
-    ythTzHourColon              => ythTzMinute1
-    ythTzMinute1                => ythTzMinute2
-    [ythInt, ythDecimal, ythExponent, ythFraction] => nil
-  of '1'..'9':
+  of '0'..'9':
     ythInitial                        => ythInt1
     ythInt1                           => ythInt2
-    ythInt1Zero                       => ythInt2Zero
     ythInt2                           => ythInt3
-    ythInt2Zero                       => ythInt3Zero
     ythInt3                           => ythInt4
-    ythInt3Zero                       => ythInt4Zero
-    [ythInt4, ythMinus]               => ythInt
+    [ythInt4, ythMinus, ythPlus]      => ythInt
     [ythNumE, ythNumEPlusMinus]       => ythExponent
     ythYearMinus                      => ythMonth1
     ythMonth1                         => ythMonth2
@@ -185,35 +151,33 @@ template advanceTypeHint(ch: char) {.dirty.} =
     ythTzHour1                        => ythTzHour2
     ythTzHourColon                    => ythTzMinute1
     ythTzMinute1                      => ythTzMinute2
+    ythPoint                          => ythDecimal
     [ythInt, ythDecimal, ythExponent, ythFraction] => nil
   of 'a':
-    ythF           => ythLowerFA
-    ythPointN      => ythPointNA
-    ythPointLowerN => ythPointLowerNA
+    [ythF, ythLowerF] => ythLowerFA
+    ythPointN         => ythPointNA
+    ythPointLowerN    => ythPointLowerNA
   of 'A':
     ythF      => ythFA
     ythPointN => ythPointNA
   of 'e':
-    [yth0, ythInt, ythDecimal] => ythNumE
+    [ythInt, ythDecimal,
+      ythInt1, ythInt2, ythInt3, ythInt4] => ythNumE
     ythLowerFALS => ythFALSE
     ythLowerTRU  => ythTRUE
-    ythY         => ythLowerYE
   of 'E':
-    [yth0, ythInt, ythDecimal] => ythNumE
+    [ythInt, ythDecimal,
+      ythInt1, ythInt2, ythInt3, ythInt4] => ythNumE
     ythFALS => ythFALSE
     ythTRU  => ythTRUE
-    ythY    => ythYE
   of 'f':
-    ythInitial      => ythF
-    ythO            => ythLowerOF
-    ythLowerOF      => ythOFF
+    ythInitial      => ythLowerF
     ythPointLowerIN => ythPointINF
   of 'F':
     ythInitial => ythF
-    ythO       => ythOF
-    ythOF      => ythOFF
     ythPointIN => ythPointINF
-  of 'i', 'I': ythPoint => ythPointI
+  of 'i': ythPoint => ythPointLowerI
+  of 'I': ythPoint => ythPointI
   of 'l':
     ythLowerNU  => ythLowerNUL
     ythLowerNUL => ythNULL
@@ -223,38 +187,33 @@ template advanceTypeHint(ch: char) {.dirty.} =
     ythNUL => ythNULL
     ythFA  => ythFAL
   of 'n':
-    ythInitial      => ythN
-    ythO            => ythON
+    ythInitial      => ythLowerN
     ythPoint        => ythPointLowerN
-    ythPointI       => ythPointLowerIN
+    [ythPointI, ythPointLowerI] => ythPointLowerIN
     ythPointLowerNA => ythPointNAN
   of 'N':
     ythInitial => ythN
-    ythO       => ythON
     ythPoint   => ythPointN
     ythPointI  => ythPointIN
     ythPointNA => ythPointNAN
-  of 'o', 'O':
-    ythInitial => ythO
-    ythN       => ythNO
-  of 'r': ythT => ythLowerTR
+  of 'r': [ythT, ythLowerT] => ythLowerTR
   of 'R': ythT => ythTR
   of 's':
     ythLowerFAL => ythLowerFALS
-    ythLowerYE  => ythYES
   of 'S':
     ythFAL => ythFALS
-    ythYE  => ythYES
-  of 't', 'T':
+  of 't':
+    ythInitial         => ythLowerT
+    [ythDay1, ythDay2, ythDay1NoYmd, ythDay2NoYmd] => ythAfterDayT
+  of 'T':
     ythInitial         => ythT
     [ythDay1, ythDay2, ythDay1NoYmd, ythDay2NoYmd] => ythAfterDayT
   of 'u':
-    ythN       => ythLowerNU
-    ythLowerTR => ythLowerTRU
+    [ythN, ythLowerN]  => ythLowerNU
+    ythLowerTR         => ythLowerTRU
   of 'U':
     ythN  => ythNU
     ythTR => ythTRU
-  of 'y', 'Y': ythInitial => ythY
   of 'Z': [ythSecond2, ythFraction, ythAfterTimeSpace] => ythAfterTimeZ
   of ' ', '\t':
     [ythSecond2, ythFraction] => ythAfterTimeSpace
@@ -268,9 +227,9 @@ proc guessType*(scalar: string): TypeHint {.raises: [].} =
   for c in scalar: advanceTypeHint(c)
   case typeHintState
   of ythNULL, ythInitial: result = yTypeNull
-  of ythTRUE, ythON, ythYES, ythY: result = yTypeBoolTrue
-  of ythFALSE, ythOFF, ythNO, ythN: result = yTypeBoolFalse
-  of ythInt1, ythInt2, ythInt3, ythInt4, ythInt, yth0, ythInt1Zero: result = yTypeInteger
+  of ythTRUE: result = yTypeBoolTrue
+  of ythFALSE: result = yTypeBoolFalse
+  of ythInt1, ythInt2, ythInt3, ythInt4, ythInt: result = yTypeInteger
   of ythDecimal, ythExponent: result = yTypeFloat
   of ythPointINF: result = yTypeFloatInf
   of ythPointNAN: result = yTypeFloatNaN