diff --git a/alib2/src/alphabet/BlankSymbol.h b/alib2/src/alphabet/BlankSymbol.h
index 25bfcb4a3426683348fae384140d7535de097256..7f330893e7ea9d6a017e281033a7df19f0848721 100644
--- a/alib2/src/alphabet/BlankSymbol.h
+++ b/alib2/src/alphabet/BlankSymbol.h
@@ -2,7 +2,7 @@
  * BlankSymbol.h
  *
  *  Created on: Mar 26, 2013
- *      Author: Jan Trávníček
+ *      Author: Jan Travnicek
  */
 
 #ifndef BLANK_SYMBOL_H_
diff --git a/alib2/src/alphabet/BottomOfTheStackSymbol.cpp b/alib2/src/alphabet/BottomOfTheStackSymbol.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7aa1015591df86eb7286e9ef27c148b0fa40b606
--- /dev/null
+++ b/alib2/src/alphabet/BottomOfTheStackSymbol.cpp
@@ -0,0 +1,54 @@
+/*
+ * BottomOfTheStackSymbol.cpp
+ *
+ *  Created on: Jun 19, 2014
+ *      Author: Jan Travnicek
+ */
+
+#include "BottomOfTheStackSymbol.h"
+
+namespace alphabet {
+
+BottomOfTheStackSymbol::BottomOfTheStackSymbol() {
+
+}
+
+SymbolBase* BottomOfTheStackSymbol::clone() const {
+	return new BottomOfTheStackSymbol(*this);
+}
+
+SymbolBase* BottomOfTheStackSymbol::plunder() && {
+	return new BottomOfTheStackSymbol(std::move(*this));
+}
+
+bool BottomOfTheStackSymbol::operator <(const SymbolBase& other) const {
+	return other > *this;
+}
+
+bool BottomOfTheStackSymbol::operator ==(const SymbolBase& other) const {
+	return other == *this;
+}
+
+bool BottomOfTheStackSymbol::operator >(const SymbolBase& other) const {
+	return other < *this;
+}
+
+bool BottomOfTheStackSymbol::operator ==(const BottomOfTheStackSymbol&) const {
+	return true;
+}
+
+bool BottomOfTheStackSymbol::operator <(const BottomOfTheStackSymbol&) const {
+	return false;
+}
+
+void BottomOfTheStackSymbol::operator>>(std::ostream& out) const {
+	out << "(Blank symbol)";
+}
+
+BottomOfTheStackSymbol::operator std::string () const {
+	return "";
+}
+
+BottomOfTheStackSymbol BottomOfTheStackSymbol::BOTTOM_OF_THE_STACK = BottomOfTheStackSymbol();
+
+} /* namespace alphabet */
diff --git a/alib2/src/alphabet/BottomOfTheStackSymbol.h b/alib2/src/alphabet/BottomOfTheStackSymbol.h
new file mode 100644
index 0000000000000000000000000000000000000000..eebc152cca9d73f6665ccf505e810fecc2c88c71
--- /dev/null
+++ b/alib2/src/alphabet/BottomOfTheStackSymbol.h
@@ -0,0 +1,45 @@
+/*
+ * BottomOfTheStackSymbol.h
+ *
+ *  Created on: Jun 19, 2014
+ *      Author: Jan Travnicek
+ */
+
+#ifndef BOTTOM_OF_THE_STACK_SYMBOL_H_
+#define BOTTOM_OF_THE_STACK_SYMBOL_H_
+
+#include "Symbol.h"
+
+namespace alphabet {
+
+/**
+ * Represents blank symbol in an alphabet.
+ */
+class BottomOfTheStackSymbol : public std::element<BottomOfTheStackSymbol, SymbolBase> {
+public:
+	/**
+	 * Creates a blank symbol.
+	 * @param symbol name of the symbol
+	 */
+	BottomOfTheStackSymbol();
+
+	virtual SymbolBase* clone() const;
+	virtual SymbolBase* plunder() &&;
+	
+	virtual bool operator <(const SymbolBase& other) const;
+	virtual bool operator ==(const SymbolBase& other) const;
+	virtual bool operator >(const SymbolBase& other) const;
+
+	virtual bool operator ==(const BottomOfTheStackSymbol& other) const;
+	virtual bool operator <(const BottomOfTheStackSymbol& other) const;
+
+	virtual void operator>>(std::ostream& out) const;
+	
+	virtual operator std::string () const;
+
+	static BottomOfTheStackSymbol BOTTOM_OF_THE_STACK;
+};
+
+} /* namespace alphabet */
+
+#endif /* BOTTOM_OF_THE_STACK_SYMBOL_H_ */
diff --git a/alib2/src/alphabet/SymbolBase.cpp b/alib2/src/alphabet/SymbolBase.cpp
index 58e7c3300ec84b0bfc9261ffffc2d6f34ce66221..9027bb867202d7e09bad09342187231ae0f5ba1b 100644
--- a/alib2/src/alphabet/SymbolBase.cpp
+++ b/alib2/src/alphabet/SymbolBase.cpp
@@ -10,6 +10,7 @@
 
 #include "LabeledSymbol.h"
 #include "BlankSymbol.h"
+#include "BottomOfTheStackSymbol.h"
 
 namespace alphabet {
 
@@ -34,6 +35,10 @@ bool SymbolBase::operator==(const BlankSymbol&) const {
 	return false;
 }
 
+bool SymbolBase::operator==(const BottomOfTheStackSymbol&) const {
+	return false;
+}
+
 bool SymbolBase::operator<(const LabeledSymbol& other) const {
 	return typeid(*this).before(typeid(other));
 }
@@ -42,4 +47,8 @@ bool SymbolBase::operator<(const BlankSymbol& other) const {
 	return typeid(*this).before(typeid(other));
 }
 
+bool SymbolBase::operator<(const BottomOfTheStackSymbol& other) const {
+	return typeid(*this).before(typeid(other));
+}
+
 } /* namespace alphabet */
diff --git a/alib2/src/alphabet/SymbolBase.h b/alib2/src/alphabet/SymbolBase.h
index 8b61aa1e2a13e5a5a79e7d7d89c8a0dd8e7d6f01..7aee1dd6768166e1fff53830ee6af5fe36fd1aa6 100644
--- a/alib2/src/alphabet/SymbolBase.h
+++ b/alib2/src/alphabet/SymbolBase.h
@@ -15,11 +15,12 @@ namespace alphabet {
 
 class LabeledSymbol;
 class BlankSymbol;
+class BottomOfTheStackSymbol;
 
 /**
  * Represents symbol in an alphabet.
  */
-class SymbolBase : public std::elementBase<LabeledSymbol, BlankSymbol> {
+class SymbolBase : public std::elementBase<LabeledSymbol, BlankSymbol, BottomOfTheStackSymbol> {
 public:
 	virtual ~SymbolBase() noexcept;
 
@@ -33,9 +34,11 @@ public:
 
 	virtual bool operator==(const LabeledSymbol& other) const;
 	virtual bool operator==(const BlankSymbol& other) const;
+	virtual bool operator==(const BottomOfTheStackSymbol& other) const;
 
 	virtual bool operator<(const LabeledSymbol& other) const;
 	virtual bool operator<(const BlankSymbol& other) const;
+	virtual bool operator<(const BottomOfTheStackSymbol& other) const;
 
 	friend std::ostream& operator<<(std::ostream&, const SymbolBase&);
 
diff --git a/alib2/src/alphabet/SymbolFromStringLexer.cpp b/alib2/src/alphabet/SymbolFromStringLexer.cpp
index 281064ae2ad4222ab813858b95ed40afc066c67c..aad58e353c3bb1803e48685dd1dd521449264e32 100644
--- a/alib2/src/alphabet/SymbolFromStringLexer.cpp
+++ b/alib2/src/alphabet/SymbolFromStringLexer.cpp
@@ -37,6 +37,9 @@ L1:
 	} else if(character == 'B') {
 		m_Current.type = TokenType::BLANK;
 		return *this;
+	} else if(character == 'Z') {
+		m_Current.type = TokenType::BOTTOM;
+		return *this;
 	} else {
 		m_In.seekg(pos);
 		m_Current.type = TokenType::ERROR;
diff --git a/alib2/src/alphabet/SymbolFromStringLexer.h b/alib2/src/alphabet/SymbolFromStringLexer.h
index 5667d05ebed16ca1dafa6241eaf679f75103d33b..83f46d61ad88dd3cd8906204b1999d7cd9e07a1b 100644
--- a/alib2/src/alphabet/SymbolFromStringLexer.h
+++ b/alib2/src/alphabet/SymbolFromStringLexer.h
@@ -10,6 +10,7 @@ class SymbolFromStringLexer {
 public:
 	enum class TokenType {
 		BLANK,
+		BOTTOM,
 		TEOF,
 		ERROR,
 	};
diff --git a/alib2/src/alphabet/SymbolFromStringParser.cpp b/alib2/src/alphabet/SymbolFromStringParser.cpp
index cf1cd464dab1d11efee2b10b8e87edbad1ceae1f..66a8635e1d96d34476ea470a8132264fe1308c21 100644
--- a/alib2/src/alphabet/SymbolFromStringParser.cpp
+++ b/alib2/src/alphabet/SymbolFromStringParser.cpp
@@ -1,6 +1,7 @@
 #include "SymbolFromStringParser.h"
 #include "../AlibException.h"
 #include "BlankSymbol.h"
+#include "BottomOfTheStackSymbol.h"
 #include "LabeledSymbol.h"
 
 namespace alphabet {
@@ -14,6 +15,8 @@ Symbol* SymbolFromStringParser::parse() {
 	switch(token.type) {
 	case SymbolFromStringLexer::TokenType::BLANK:
 		return new Symbol(BlankSymbol());
+	case SymbolFromStringLexer::TokenType::BOTTOM:
+		return new Symbol(BottomOfTheStackSymbol());
 	case SymbolFromStringLexer::TokenType::ERROR: {
 		label::Label* label = m_LabelParser.parse();
 		if(label != NULL) {
diff --git a/alib2/src/alphabet/SymbolFromXMLParser.cpp b/alib2/src/alphabet/SymbolFromXMLParser.cpp
index 92bbfa6b419d37173e88b86dcfa28f6037653edd..650cd201ccdeced3c6af2121904fe8f9dadbc03e 100644
--- a/alib2/src/alphabet/SymbolFromXMLParser.cpp
+++ b/alib2/src/alphabet/SymbolFromXMLParser.cpp
@@ -9,6 +9,7 @@
 
 #include "../sax/ParserException.h"
 #include "BlankSymbol.h"
+#include "BottomOfTheStackSymbol.h"
 #include "LabeledSymbol.h"
 #include "../label/Label.h"
 
@@ -26,6 +27,10 @@ Symbol SymbolFromXMLParser::parse(std::list<sax::Token>& input) const {
 		popToken(input, sax::Token::TokenType::START_ELEMENT, "BlankSymbol");
 		popToken(input, sax::Token::TokenType::END_ELEMENT, "BlankSymbol");
 		return Symbol(BlankSymbol());
+	} else if(isToken(input, sax::Token::TokenType::START_ELEMENT, "BottomOfTheStackSymbol")) {
+		popToken(input, sax::Token::TokenType::START_ELEMENT, "BottomOfTheStackSymbol");
+		popToken(input, sax::Token::TokenType::END_ELEMENT, "BottomOfTheStackSymbol");
+		return Symbol(BlankSymbol());
 	} else {
 		throw sax::ParserException(sax::Token("", sax::Token::TokenType::START_ELEMENT), input.front());
 	}
diff --git a/alib2/src/alphabet/SymbolToStringComposer.cpp b/alib2/src/alphabet/SymbolToStringComposer.cpp
index 5c49ef29687be52b87ccebf7f033a5fafe27410c..3788626c9486b0eb4bdcd954c66890616a577492 100644
--- a/alib2/src/alphabet/SymbolToStringComposer.cpp
+++ b/alib2/src/alphabet/SymbolToStringComposer.cpp
@@ -8,7 +8,6 @@
 #include "SymbolToStringComposer.h"
 #include "../label/LabelToStringComposer.h"
 #include <algorithm>
-#include "../label/Label.h"
 #include "LabeledSymbol.h"
 
 namespace alphabet {
@@ -26,6 +25,12 @@ void SymbolToStringComposer::Visit(void* userData, const BlankSymbol&) {
 	out << "#B";
 }
 
+void SymbolToStringComposer::Visit(void* userData, const BottomOfTheStackSymbol&) {
+	std::stringstream &out = *((std::stringstream*) userData);
+
+	out << "#Z";
+}
+
 void SymbolToStringComposer::Visit(void* userData, const Symbol& symbol) {
 	symbol.getSymbol().Accept(userData, *this);
 
diff --git a/alib2/src/alphabet/SymbolToStringComposer.h b/alib2/src/alphabet/SymbolToStringComposer.h
index 4f4b16837d64cbe0e35f2ccf58a9b0061263bd44..237e61f69c9876c07b4ccc10fbcfb9739410b7d4 100644
--- a/alib2/src/alphabet/SymbolToStringComposer.h
+++ b/alib2/src/alphabet/SymbolToStringComposer.h
@@ -22,6 +22,8 @@ class SymbolToStringComposer : public SymbolBase::visitor_type {
 	void Visit(void*, const Symbol& symbol);
 	void Visit(void*, const LabeledSymbol& symbol);
 	void Visit(void*, const BlankSymbol& symbol);
+	void Visit(void*, const BottomOfTheStackSymbol& symbol);
+
 public:
 	/**
 	 * Prints text representation of Symbol to the output stream.
diff --git a/alib2/src/alphabet/SymbolToXMLComposer.cpp b/alib2/src/alphabet/SymbolToXMLComposer.cpp
index f6a25fc10a8594d2ea87fdd8a628b23f7125d51c..cd6e06dd38859cbda7291994e1f5648a31afb8ee 100644
--- a/alib2/src/alphabet/SymbolToXMLComposer.cpp
+++ b/alib2/src/alphabet/SymbolToXMLComposer.cpp
@@ -6,7 +6,6 @@
  */
 
 #include "SymbolToXMLComposer.h"
-#include "LabeledSymbol.h"
 
 #include "../ToXMLComposers.h"
 
@@ -19,6 +18,13 @@ void SymbolToXMLComposer::Visit(void* userData, const BlankSymbol&) const {
 	out.push_back(sax::Token("BlankSymbol", sax::Token::TokenType::END_ELEMENT));
 }
 
+void SymbolToXMLComposer::Visit(void* userData, const BottomOfTheStackSymbol&) const {
+	std::list<sax::Token> &out = *((std::list<sax::Token>*) userData);
+
+	out.push_back(sax::Token("BottomOfTheStackSymbol", sax::Token::TokenType::START_ELEMENT));
+	out.push_back(sax::Token("BottomOfTheStackSymbol", sax::Token::TokenType::END_ELEMENT));
+}
+
 void SymbolToXMLComposer::Visit(void* userData, const LabeledSymbol& symbol) const {
 	std::list<sax::Token> &out = *((std::list<sax::Token>*) userData);
 
diff --git a/alib2/src/alphabet/SymbolToXMLComposer.h b/alib2/src/alphabet/SymbolToXMLComposer.h
index ab826bfd79ff6778322b3fe2a2a597fcb4614150..e83d301fb06b16f8bcf5b599cf08b9864589d90c 100644
--- a/alib2/src/alphabet/SymbolToXMLComposer.h
+++ b/alib2/src/alphabet/SymbolToXMLComposer.h
@@ -22,6 +22,7 @@ class SymbolToXMLComposer : public SymbolBase::const_visitor_type {
 	void Visit(void*, const Symbol& symbol) const;
 	void Visit(void*, const LabeledSymbol& symbol) const;
 	void Visit(void*, const BlankSymbol& symbol) const;
+	void Visit(void*, const BottomOfTheStackSymbol& symbol) const;
 
 public:
 	/**
diff --git a/alib2/src/label/LabelFromXMLParser.cpp b/alib2/src/label/LabelFromXMLParser.cpp
index 66b345c04035c47992ffa212961400e3d3d40ca6..43995a545d69a6cde423ec080b168b5c5791031a 100644
--- a/alib2/src/label/LabelFromXMLParser.cpp
+++ b/alib2/src/label/LabelFromXMLParser.cpp
@@ -35,4 +35,4 @@ Label LabelFromXMLParser::parse(std::list<sax::Token>& input) const {
 	}
 }
 
-} /* namespace string */
+} /* namespace label */