there is a measurement the elements <value> (3.6.3) or <value_min> (3.6.4) and <value_max> (3.6.5) is/are mandatory if <measure_code> (3.6.2) is either "DIS", "VER", "LSD" or "WAL".
 In case there is no measurement (and a message should be sent anyhow) the value elements shall be omitted.
 11.
 Element <barrage_code> (3.6.7) is mandatory if <measure code> (3.6.2) is "BAR".
 12.
 Element <regime_code> (3.6.8) is mandatory if <measure code> (3.6.2) is "REG".
 13.
 Predictions for more than one <validity_period> (5.3) require individual <werm> messages.
 14.
 In case of <icem> (4.4.2) and <werm> a <limitation> section is not applicable. Limitations shall be provided via FTM notices.
 <?xml version="1.0" encoding="UTF-8"?>
 <xs:schema xmlns:nts="http://www.ris.eu/nts/4.0.4.0" xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace=">http://www.ris.eu/nts/4.0.4.0" elementFormDefault="qualified" attributeFormDefault="unqualified" version="4.0.4.0">
 <!--
 ===========================================
 = definition of main element RIS_Message =
 = and corresponding type RIS_Message_Type =
 ===========================================
 -->
 <xs:element name="RIS_Message" type="nts:RIS_Message_Type">
 <xs:annotation>
 <xs:documentation>River Information Service Message</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:complexType name="RIS_Message_Type">
 <xs:sequence>
 <xs:element name="identification" type="nts:identification_type">
 <xs:annotation>
 <xs:documentation>Identification section</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:choice>
 <xs:annotation>
 <xs:documentation>One msg contains one of these sections</xs:documentation>
 </xs:annotation>
 <xs:element name="ftm" type="nts:ftm_type" maxOccurs="unbounded">
 <xs:annotation>
 <xs:documentation>Fairway and traffic related section</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:element name="wrm" type="nts:wrm_type" maxOccurs="unbounded">
 <xs:annotation>
 <xs:documentation>Water related section</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:element name="icem" type="nts:icem_type" maxOccurs="unbounded">
 <xs:annotation>
 <xs:documentation>Ice related section</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:element name="werm" type="nts:werm_type" maxOccurs="unbounded">
 <xs:annotation>
 <xs:documentation>Weather related section</xs:documentation>
 </xs:annotation>
 </xs:element>
 </xs:choice>
 </xs:sequence>
 </xs:complexType>
 <!--
 ==========================================
 = definition of identification_type, =
 = used in definition of RIS_Message_Type =
 ==========================================
 -->
 <xs:complexType name="identification_type">
 <xs:sequence>
 <xs:element name="internal_id" type="nts:internal_id_type" minOccurs="0">
 <xs:annotation>
 <xs:documentation>Internal ID</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:element name="from">
 <xs:annotation>
 <xs:documentation>Sender (System) of the message</xs:documentation>
 </xs:annotation>
 <xs:simpleType>
 <xs:restriction base="xs:string">
 <xs:maxLength value="64"/>
 </xs:restriction>
 </xs:simpleType>
 </xs:element>
 <xs:element name="originator">
 <xs:annotation>
 <xs:documentation>Originator (initiator) of the information in this message</xs:documentation>
 </xs:annotation>
 <xs:simpleType>
 <xs:restriction base="xs:string">
 <xs:maxLength value="64"/>
 </xs:restriction>
 </xs:simpleType>
 </xs:element>
 <xs:element name="country_code" type="nts:country_code_enum">
 <xs:annotation>
 <xs:documentation>Country where message is valid</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:element name="language_code" type="nts:language_code_enum">
 <xs:annotation>
 <xs:documentation>Original language used in the textual info. (contents)</xs:documentation>
 </xs:annotation>
 </xs:element>
 <xs:element name="district" minOccurs="0">
 <xs:annotation>
 <xs:documentation>District / Region within the specified country, where the message is applicable</xs:documentation>
 </xs:annotation>
 <xs:simpleType>
 <xs:restriction base="xs:string">
 <xs:maxLength value="64"/>
 </xs:restriction>
 </xs:simpleType>
 </xs:element>
 <xs:element name="date_issue" type="xs:dateTime">
 <xs:annotation>
 <xs:documentation>Date and time of publication including time zone</xs:documentation>
 </xs:annotation>
 </xs:element>
 </xs:sequence>
 </xs:complexType>
 <!--
 ===================================================
 = types used in definition of identification_type =
 ===================================================
 -->
 <xs:simpleType name="country_code_enum">
 <xs:restriction base="xs:string">
 <xs:maxLength value="2"/>
 <xs:enumeration value="AT"/>
 <xs:enumeration value="BE"/>
 <xs:enumeration value="BG"/>
 <xs:enumeration value="CH"/>
 <xs:enumeration value="CY"/>
 <xs:enumeration value="CZ"/>
 <xs:enumeration value="DE"/>
 <xs:enumeration value="DK"/>
 <xs:enumeration value="EE"/>
 <xs:enumeration value="ES"/>
 <xs:enumeration value="FI"/>
 <xs:enumeration value="FR"/>
 <xs:enumeration value="GB"/>
 <xs:enumeration value="GR"/>
 <xs:enumeration value="HR"/>
 <xs:enumeration value="HU"/>
 <xs:enumeration value="IE"/>
 <xs:enumeration value="IT"/>
 <xs:enumeration value="LT"/>
 <xs:enumeration value="LU"/>
 <xs:enumeration value="LV"/>
 <xs:enumeration value="MD"/>
 <xs:enumeration value="ME"/>
 <xs:enumeration value="MT"/>
 <xs:enumeration value="NL"/>
 <xs:enumeration value="PL"/>
 <xs:enumeration value="PT"/>
 <xs:enumeration value="RO"/>
 <xs:enumeration value="RS"/>
 <xs:enumeration value="SE"/>
 <xs:enumeration value="SI"/>
 <xs:enumeration value="SK"/>
 <xs:enumeration value="RU"/>
 <xs:enumeration value="UA"/>
 </xs:restriction>
 </xs:simpleType>
 <xs:simpleType name="language_code_enum">
 <xs:restriction base="xs:string">
 <xs:maxLength value="2"/>
 <xs:enumeration value="DE"/>
 <xs:enumeration value="EN"/>
 <xs:enumeration value="FR"/>
 <xs:enumeration value="NL"/>
 <xs:enumeration value="SK"/>
 <xs:enumeration value="HU"/>
 <xs:enumeration value="HR"/>
 <xs:enumeration value="SR"/>
 <xs:enumeration value="BG"/>
 <xs:enumeration value="RO"/>
 <xs:enumeration value="RU"/>
 <xs:enumeration value="CS"/>
 <xs:enumeration value="PL"/>
 <xs:enumeration value="PT"/>
 <xs:enumeration value="ES"/>
 <xs:enumeration value="SV"/>
 <xs:enumeration value="FI"/>
 <xs:enumeration value="DA"/>
 <xs:enumeration value="ET"/>
 <xs:enumeration value="LV"/>
 <xs:enumeration value="LT"/>
 <xs:enumeration value="IT"/>
 <xs:enumeration value="MT"/>
 <xs:enumeration value="EL"/>
 <xs:enumeration value="SL"/>
 </xs:restriction>
 </xs:simpleType>
 <!--
 ==========================================
 = definition of ftm_type, =
 = used in definition of RIS_Message_Type =
 ==========================================
 -->
 <xs:complexType name="ftm_type">
