--- a/include/DataTypeWriterBase.h	Fri Jul 13 23:02:09 2018 +0200
+++ b/include/DataTypeWriterBase.h	Sat Jul 14 13:14:20 2018 +0200
@@ -22,8 +22,22 @@
 	virtual ~DataTypeWriterBase() {
 	};
 
+	/**
+	 * @param input input stream, should be at position where the value is to be read; the stream will not be closed afred reading
+	 * @return read value in form of the string representation of given data type.
+	 * E.g. integer 123 is returned as a character string "123",
+	 * boolean true is returned as a character string "true".
+	 * See Relational pipes format specification for details.
+	 */
 	virtual string_t readString(std::istream &input) = 0;
 
+	/**
+	 * @param output output stream, should be at position where the value is to be written; the stream will not be closed not flushed after writing
+	 * @param stringValue write value as given data type (e.g. integer or boolean); stringValue parameter contains given value in string representation of given data type
+	 * E.g. integer 123 is passed as a character string "123"
+	 * boolean true is passed as a character string "true".
+	 * See Relational pipes format specification for details.
+	 */
 	virtual void writeString(std::ostream& output, const string_t &stringValue) = 0;
 
 	/**