diff --git a/CMakeLists.txt b/CMakeLists.txt
index 85921c43..a053f52a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.0)
 cmake_policy(SET CMP0017 NEW) # need include() with .cmake
 project(pip)
 set(_PIP_MAJOR    1)
-set(_PIP_MINOR    17)
+set(_PIP_MINOR    18)
 set(_PIP_REVISION 0)
 set(_PIP_SUFFIX   alpha)
 set(_PIP_COMPANY  SHS)
diff --git a/README.md b/README.md
index 23056ec2..6b6fe825 100644
--- a/README.md
+++ b/README.md
@@ -30,3 +30,7 @@ You should add ${<out_var>} to your target.
 
 Generate C++ files for resource file.
 You should add ${<out_var>} to your target.
+
+## Documentation
+
+[Online documentation](https://shs.tools/pip/html/index.html)
diff --git a/doc/examples/pistring.cpp b/doc/examples/pistring.cpp
index 6ad2423f..0d9323bb 100644
--- a/doc/examples/pistring.cpp
+++ b/doc/examples/pistring.cpp
@@ -211,6 +211,16 @@ piCout << s.find("3"); // 9
 piCout << s.find("3", 4); // 9
 piCout << s.find("3", 10); // -1
 //! [PIString::findLast]
+//! [PIString::findAny]
+piCout << PIString("1.str").findAny(".,:"); // 1
+piCout << PIString("1,str").findAny(".,:"); // 1
+piCout << PIString("1:str").findAny(".,:"); // 1
+//! [PIString::findAny]
+//! [PIString::findAnyLast]
+piCout << PIString("str.0").findAny(".,:"); // 3
+piCout << PIString("str,0").findAny(".,:"); // 3
+piCout << PIString("str:0").findAny(".,:"); // 3
+//! [PIString::findAnyLast]
 //! [PIString::findWord]
 PIString s("this is <PIP>");
 piCout << s.find("this"); // 0
diff --git a/src_main/core/pistring.cpp b/src_main/core/pistring.cpp
index 3cc9dca2..6e952f93 100755
--- a/src_main/core/pistring.cpp
+++ b/src_main/core/pistring.cpp
@@ -68,6 +68,48 @@
  */
 
 
+/*! \fn int versionCompare(const PIString & v0, const PIString & v1, int components = 6)
+ * \relatesalso PIString
+ * \brief Compare two version strings in free notation and returns 0, -1 or 1
+ * \details This function parse version to number codes and labels. Then it
+ * compare no more than "components" codes. If there is no difference, compare
+ * labels. Each label has corresponding integer value, so
+ * "prealpha" < "alpha" < "prebeta" < "beta" < "rcN" < "" < "rN".
+ * Example:
+ * \code
+ * piCout << versionCompare("1.0.0_rc2-999", "1.0.1_rc2-999"); // -1
+ * piCout << versionCompare("1.0.0", "0.9.2"); // 1
+ * piCout << versionCompare("1.0.0_r1", "1.0.0"); // 1
+ * piCout << versionCompare("1.0.0_r1", "1.0.0", 3); // 0
+ * piCout << versionCompare("1.0.0_r1", "1.0.0", 3); // 0
+ * piCout << versionCompare(".2-alpha", "0.2_alpha"); // 0
+ * piCout << versionCompare("1_prebeta", "1.0_alpha"); // 1
+ * \endcode
+ * \return
+ * * 0 - equal
+ * * 1 - v0 > v1
+ * * -1 - v0 < v1
+ *
+ *
+ * \fn PIString versionNormalize(const PIString & v)
+ * \relatesalso PIString
+ * \brief Converts version string in free notation to classic view
+ * \details Parse version as described in \a versionCompare() and
+ * returns classic view of codes and labels: major.minor.revision[-build][_label].
+ * Example:
+ * \code
+ * piCout << versionNormalize(""); // 0.0.0
+ * piCout << versionNormalize("1"); // 1.0.0
+ * piCout << versionNormalize("1.2"); // 1.2.0
+ * piCout << versionNormalize("1.2.3"); // 1.2.3
+ * piCout << versionNormalize("1.2+rc1.99"); // 1.2.99_rc1
+ * piCout << versionNormalize("1.2-alpha"); // 1.2.0_alpha
+ * piCout << versionNormalize("1..4_rc2-999"); // 1.0.4-999_rc2
+ * \endcode
+ *
+ */
+
+
 const char PIString::toBaseN[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
 									'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
 									'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
@@ -760,6 +802,30 @@ int PIString::findRange(const PIChar & start, const PIChar & end, const PIChar &
 }
 
 
+int PIString::findAny(const PIString & str, const int start) const {
+	for (int i = start; i < length(); ++i)
+		if (str.contains(at(i)))
+			return i;
+	return -1;
+}
+
+
+int PIString::findAnyLast(const PIString & str, const int start) const {
+	for (int i = length() - 1; i >= start; --i)
+		if (str.contains(at(i)))
+			return i;
+	return -1;
+}
+
+
+int PIString::entries(const PIChar & c) const {
+	int sz = size_s(), ret = 0;
+	for (int i = 0; i < sz; ++i)
+		if (at(i) == c) ++ret;
+	return ret;
+}
+
+
 bool PIString::startsWith(const PIString & str) const {
 	if (size() < str.size()) return false;
 	return str == left(str.size());
@@ -1110,6 +1176,117 @@ inline char chrLwr(char c) {
 }
 
 
+const static PIString _versionDelims_ = PIStringAscii("._-+");
+
+void parseVersion(PIString s, PIVector<int> & codes, PIStringList & strs) {
+	s.trim();
+	if (s.isEmpty()) {
+		codes.resize(3, 0);
+		return;
+	}
+	int mccnt = 2 - s.entries('.');
+	if (mccnt > 0) {
+		int ind = s.findLast(".") + 1;
+		while (!_versionDelims_.contains(s[ind])) {
+			++ind;
+			if (ind > s.size_s() - 1)
+				break;
+		}
+		for (int i = 0; i < mccnt; ++i)
+			s.insert(ind, ".0");
+	}
+	PIStringList comps;
+	while (!s.isEmpty()) {
+		int ind = s.findAny(_versionDelims_);
+		if (ind >= 0) {
+			comps << s.takeLeft(ind);
+			s.cutLeft(1).trim();
+		} else {
+			comps << s;
+			s.clear();
+		}
+	}
+	for (int i = 0; i < comps.size_s(); ++i) {
+		if (comps[i].isEmpty())
+			comps[i] = "0";
+		bool ok = false;
+		int val = comps[i].toInt(-1, &ok);
+		if (ok) {
+			codes << val;
+		} else {
+			strs << comps[i];
+		}
+	}
+	//piCout << codes << strs;
+}
+
+int versionLabelValue(PIString s) {
+	int ret = -10000;
+	if (s.isEmpty()) return 0;
+	if (s.startsWith("pre")) {
+		s.cutLeft(3);
+		ret -= 1;
+	}
+	if (s.startsWith("rc")) {
+		s.cutLeft(2);
+		ret += s.toInt();
+	}
+	if (s.startsWith("r")) {
+		s.cutLeft(1);
+		ret += 10000 + s.toInt();
+	}
+	if (s == "alpha") ret -= 4;
+	if (s == "beta" ) ret -= 2;
+	return ret;
+}
+
+int versionCompare(const PIString & v0, const PIString & v1, int components) {
+	PIStringList strs[2]; PIVector<int> codes[2];
+	parseVersion(v0.toLowerCase(), codes[0], strs[0]);
+	parseVersion(v1.toLowerCase(), codes[1], strs[1]);
+	//piCout << codes[0] << strs[0];
+	int mc = piMaxi(codes[0].size_s(), codes[1].size_s());
+	if (codes[0].size_s() < mc) codes[0].resize(mc, 0);
+	if (codes[1].size_s() < mc) codes[1].resize(mc, 0);
+	mc = piMaxi(strs[0].size_s(), strs[1].size_s());
+	if (strs[0].size_s() < mc) strs[0].resize(mc, "");
+	if (strs[1].size_s() < mc) strs[1].resize(mc, "");
+	int comps = piMini(components, codes[0].size_s(), codes[1].size_s());
+	if (comps < 1) return (v0 == v1 ? 0 : (v0 > v1 ? 1 : -1));
+	for (int c = 0; c < comps; ++c) {
+		if (codes[0][c] > codes[1][c]) return  1;
+		if (codes[0][c] < codes[1][c]) return -1;
+	}
+	mc = piClampi(mc, 0, components - comps);
+	for (int c = 0; c < mc; ++c) {
+		int lv0 = versionLabelValue(strs[0][c]);
+		int lv1 = versionLabelValue(strs[1][c]);
+		if (lv0 > lv1) return  1;
+		if (lv0 < lv1) return -1;
+	}
+	return 0;
+}
+
+
+PIString versionNormalize(const PIString & v) {
+	PIStringList strs; PIVector<int> codes;
+	parseVersion(v.toLowerCase(), codes, strs);
+	PIString ret;
+	for (int i = 0; i < codes.size_s(); ++i) {
+		if (i > 0) {
+			if (i < 3) ret += ".";
+			else ret += "-";
+		}
+		ret += PIString::fromNumber(codes[i]);
+	}
+	for (int i = 0; i < strs.size_s(); ++i) {
+		ret += "_";
+		ret += strs[i];
+	}
+	return ret;
+}
+
+
 PICout operator <<(PICout s, const PIString & v) {
 	s.space();
 	s.quote();
@@ -1146,4 +1323,3 @@ PIStringList& PIStringList::removeDuplicates() {
 	}
 	return *this;
 }
-
diff --git a/src_main/core/pistring.h b/src_main/core/pistring.h
index b6591bf5..c0bf5cc7 100755
--- a/src_main/core/pistring.h
+++ b/src_main/core/pistring.h
@@ -547,7 +547,29 @@ public:
 	//! \brief Search range between "start" and "end" symbols at index "start_index" and return first occur position.
 	//! \details Example: \snippet pistring.cpp PIString::findRange
 	int findRange(const PIChar & start, const PIChar & end, const PIChar & shield = '\\', const int start_index = 0, int * len = 0) const;
-	
+
+	//! \brief Search any symbol of "str" from symbol at index "start" and return first occur position
+	//! \details Example: \snippet pistring.cpp PIString::findAny
+	int findAny(const PIString & str, const int start = 0) const;
+
+	//! \brief Search any symbol of "str" from symbol at index "start" and return first occur position
+	//! \details Example: \snippet pistring.cpp PIString::findAny
+	int findAny(const char * str, const int start = 0) const {return findAny(PIString(str), start);}
+
+	//! \brief Search any symbol of "str" from symbol at index "start" and return last occur position
+	//! \details Example: \snippet pistring.cpp PIString::findAnyLast
+	int findAnyLast(const PIString & str, const int start = 0) const;
+
+	//! \brief Search any symbol of "str" from symbol at index "start" and return last occur position
+	//! \details Example: \snippet pistring.cpp PIString::findAnyLast
+	int findAnyLast(const char * str, const int start = 0) const {return findAnyLast(PIString(str), start);}
+
+	//! \brief Returns number of occurrences of symbol "c"
+	int entries(const PIChar & c) const;
+
+	//! \brief Returns number of occurrences of symbol "c"
+	int entries(char c) const {return entries(PIChar(c));}
+
 	//! \brief Return if string starts with "str"
 	bool startsWith(const PIString & str) const;
 	
@@ -785,6 +807,11 @@ inline char chrUpr(char c);
 inline char chrLwr(char c);
 
 
+int versionCompare(const PIString & v0, const PIString & v1, int components = 6);
+
+PIString versionNormalize(const PIString & v);
+
+
 /*!\brief Strings array class
  * \details This class is based on \a PIDeque<PIString> and
  * expand it functionality. */
diff --git a/src_main/io_devices/piserial.cpp b/src_main/io_devices/piserial.cpp
index a83691c6..b0301d2a 100755
--- a/src_main/io_devices/piserial.cpp
+++ b/src_main/io_devices/piserial.cpp
@@ -143,7 +143,7 @@
  * This class provide access to serial device, e.g. COM port. It can read,
  * write, wait for write. There are several read and write functions.
  *
- * \section  PISerial_sec0 FullPath
+ * \section  PISerial_sec1 FullPath
  * Since version 1.16.0 you can use as \a path DeviceInfo::id() USB identifier.
  * \code
  * PISerial * s = new PISerial("0403:6001");