diff --git a/doc/README.cast.format.md b/doc/sql.extensions/README.cast.format.md
similarity index 100%
rename from doc/README.cast.format.md
rename to doc/sql.extensions/README.cast.format.md
diff --git a/src/common/CvtFormat.cpp b/src/common/CvtFormat.cpp
index 301c1e25fb2..ce483c15493 100644
--- a/src/common/CvtFormat.cpp
+++ b/src/common/CvtFormat.cpp
@@ -1194,6 +1194,31 @@ namespace
 		return std::string_view(str + startPoint, wordLen);
 	}
 
+	constexpr unsigned getFractionsFromString(const char* str, FB_SIZE_T length, FB_SIZE_T& offset, FB_SIZE_T parseLength)
+	{
+		constexpr unsigned pow10[] = {1, 10, 100, 1'000, 10'000};
+		static_assert(std::size(pow10) > -ISC_TIME_SECONDS_PRECISION_SCALE);
+
+		if (parseLength > -ISC_TIME_SECONDS_PRECISION_SCALE)
+			parseLength = -ISC_TIME_SECONDS_PRECISION_SCALE;
+		int currentPrecisionScale = -ISC_TIME_SECONDS_PRECISION_SCALE;
+		unsigned fractions = 0;
+
+		const FB_SIZE_T parseLengthWithOffset = offset + parseLength;
+		for (; offset < parseLengthWithOffset && offset < length; offset++)
+		{
+			const char symbol = str[offset];
+
+			if (!isDigit(symbol))
+				break;
+
+			fractions = fractions * 10 + (symbol - '0');
+			--currentPrecisionScale;
+		}
+
+		return fractions * pow10[currentPrecisionScale];
+	}
+
 	template <typename TIterator>
 	constexpr TIterator getPreviousOrCurrentIterator(TIterator it, TIterator begin)
 	{
@@ -1499,10 +1524,9 @@ namespace
 				case Format::FF3:
 				case Format::FF4:
 				{
-					const int number = patternStr.back() - '0';
+					const int precision = patternStr.back() - '0';
 
-					const int fractions = getIntFromString(str, strLength, strOffset, number);
-					outFractions = fractions * pow(10, -ISC_TIME_SECONDS_PRECISION_SCALE - number);
+					outFractions = getFractionsFromString(str, strLength, strOffset, precision);
 					break;
 				}
 
diff --git a/src/common/tests/CvtTest.cpp b/src/common/tests/CvtTest.cpp
index a86f48d7a7b..6a685b891ed 100644
--- a/src/common/tests/CvtTest.cpp
+++ b/src/common/tests/CvtTest.cpp
@@ -550,25 +550,31 @@ BOOST_AUTO_TEST_CASE(CVTStringToFormatDateTime_TIME)
 	testCVTStringToFormatDateTimeExpectTime("5", "FF1", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 5000), cb);
 	testCVTStringToFormatDateTimeExpectTime("9", "FF1", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 9000), cb);
 
-	testCVTStringToFormatDateTimeExpectTime("1", "FF2", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 100), cb);
+	testCVTStringToFormatDateTimeExpectTime("01", "FF2", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 100), cb);
+	testCVTStringToFormatDateTimeExpectTime("1",  "FF2", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
 	testCVTStringToFormatDateTimeExpectTime("10", "FF2", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
 	testCVTStringToFormatDateTimeExpectTime("50", "FF2", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 5000), cb);
 	testCVTStringToFormatDateTimeExpectTime("99", "FF2", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 9900), cb);
 
-	testCVTStringToFormatDateTimeExpectTime("1", "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 10), cb);
-	testCVTStringToFormatDateTimeExpectTime("10", "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 100), cb);
+	testCVTStringToFormatDateTimeExpectTime("01",  "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 100), cb);
+	testCVTStringToFormatDateTimeExpectTime("001", "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 10), cb);
+	testCVTStringToFormatDateTimeExpectTime("1",   "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
+	testCVTStringToFormatDateTimeExpectTime("10",  "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
 	testCVTStringToFormatDateTimeExpectTime("100", "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
 	testCVTStringToFormatDateTimeExpectTime("500", "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 5000), cb);
 	testCVTStringToFormatDateTimeExpectTime("999", "FF3", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 9990), cb);
 
-	testCVTStringToFormatDateTimeExpectTime("1", "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1), cb);
-	testCVTStringToFormatDateTimeExpectTime("10", "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 10), cb);
-	testCVTStringToFormatDateTimeExpectTime("100", "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 100), cb);
+	testCVTStringToFormatDateTimeExpectTime("01",   "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 100), cb);
+	testCVTStringToFormatDateTimeExpectTime("001",  "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 10), cb);
+	testCVTStringToFormatDateTimeExpectTime("0001", "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1), cb);
+	testCVTStringToFormatDateTimeExpectTime("1",    "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
+	testCVTStringToFormatDateTimeExpectTime("10",   "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
+	testCVTStringToFormatDateTimeExpectTime("100",  "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
 	testCVTStringToFormatDateTimeExpectTime("1000", "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 1000), cb);
 	testCVTStringToFormatDateTimeExpectTime("5000", "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 5000), cb);
 	testCVTStringToFormatDateTimeExpectTime("9999", "FF4", createTimeStampTZ(0, 0, 0, 0, 0, 0, 0, 9999), cb);
 
-	testCVTStringToFormatDateTimeExpectTime("1 P.M. - 25 - 45 - 200", "HH P.M. MI.SS.FF4", createTimeStampTZ(0, 0, 0, 13, 25, 45, 0, 200), cb);
+	testCVTStringToFormatDateTimeExpectTime("1 P.M. - 25 - 45 - 2", "HH P.M. MI.SS.FF4", createTimeStampTZ(0, 0, 0, 13, 25, 45, 0, 2000), cb);
 	testCVTStringToFormatDateTimeExpectTime("15:0:15:2", "HH24.MI.SS.FF1", createTimeStampTZ(0, 0, 0, 15, 0, 15, 0, 2000), cb);
 }
 
@@ -583,7 +589,7 @@ BOOST_AUTO_TEST_CASE(CVTStringToFormatDateTime_TZ)
 
 BOOST_AUTO_TEST_CASE(CVTStringToFormatDateTime_SOLID_PATTERNS)
 {
-	testCVTStringToFormatDateTimeExpectTime("1 P.M. - 25 - 45 - 200", "HHA.M.MISSFF4", createTimeStampTZ(0, 0, 0, 13, 25, 45, 0, 200), cb);
+	testCVTStringToFormatDateTimeExpectTime("1 P.M. - 25 - 45 - 2", "HHA.M.MISSFF4", createTimeStampTZ(0, 0, 0, 13, 25, 45, 0, 2000), cb);
 	testCVTStringToFormatDateTimeExpectDate("1981-8/13", "YEARMMDD", createTimeStampTZ(1981, 8, 13, 0, 0, 0, 0), cb);
 }