<!-- DTD for the DIF                                  2004-03-04 -->

<!ELEMENT DIF ( Entry_ID, Entry_Title, Data_Set_Citation*, Personnel*,
  Discipline*, Parameters+, ISO_Topic_Category*, Keyword*, Sensor_Name*, 
  Source_Name*, Temporal_Coverage*, Paleo_Temporal_Coverage*, 
  Data_Set_Progress?, Spatial_Coverage*, Location*, Data_Resolution*, 
  Project*, Quality?, Access_Constraints?, Use_Constraints?, Data_Set_Language*,
  Originating_Center?, Data_Center+, Distribution*, 
  Multimedia_Sample*, Reference?, Summary, Related_URL*, Parent_DIF*,
  IDN_Node*, Originating_Metadata_Node?, Metadata_Name?, Metadata_Version?, 
  DIF_Creation_Date?, Last_DIF_Revision_Date?, DIF_Revision_History?, 
  Future_DIF_Review_Date?, Public? )  >

<!-- Entry ID and Title ========================================== -->

<!ELEMENT Entry_ID (#PCDATA)>

<!ELEMENT Entry_Title (#PCDATA)>

<!-- Data Set Citation =========================================== -->

<!ELEMENT Data_Set_Citation ( 
  Dataset_Creator?, Dataset_Title?, Dataset_Series_Name?, Dataset_Release_Date?, Dataset_Release_Place?,  Dataset_Publisher?, Version?, Issue_Identification?, Data_Presentation_Form?, Other_Citation_Details?, Online_Resource? )
>

<!ELEMENT Dataset_Creator (#PCDATA)>
<!ELEMENT Dataset_Title (#PCDATA)>
<!ELEMENT Dataset_Series_Name (#PCDATA)>
<!ELEMENT Dataset_Release_Date (#PCDATA)>
<!ELEMENT Dataset_Release_Place (#PCDATA)>
<!ELEMENT Dataset_Publisher (#PCDATA)>
<!ELEMENT Version (#PCDATA)>
<!ELEMENT Issue_Identification (#PCDATA)>
<!ELEMENT Data_Presentation_Form (#PCDATA)>
<!ELEMENT Other_Citation_Details (#PCDATA)>
<!ELEMENT Online_Resource (#PCDATA)>

<!-- Personnel =================================================== -->

<!ELEMENT Personnel (Role+, First_Name?, Middle_Name?, Last_Name, 
  Email*, Phone*, (Fax* | FAX*), Contact_Address?)>

<!ELEMENT Role (#PCDATA)>
<!ELEMENT First_Name (#PCDATA)>
<!ELEMENT Middle_Name (#PCDATA)>
<!ELEMENT Last_Name (#PCDATA)>
<!ELEMENT Email (#PCDATA)>
<!ELEMENT Phone (#PCDATA)>
<!ELEMENT Fax (#PCDATA)>
<!ELEMENT FAX (#PCDATA)>

<!ELEMENT Contact_Address ( Address*, City?, Province_or_State?, 
  Postal_Code?, Country?)>

<!ELEMENT Address (#PCDATA)>
<!ELEMENT City (#PCDATA)>
<!ELEMENT Province_or_State (#PCDATA)>
<!ELEMENT Postal_Code (#PCDATA)>
<!ELEMENT Country (#PCDATA)>


<!-- Discipline=================================================== -->

<!ELEMENT Discipline (Discipline_Name, Subdiscipline?, Detailed_Subdiscipline?)>
<!ELEMENT Discipline_Name (#PCDATA)>
<!ELEMENT Subdiscipline (#PCDATA)>
<!ELEMENT Detailed_Subdiscipline (#PCDATA)>

<!-- Parameters=================================================== -->

<!ELEMENT Parameters (Category, Topic, Term, Variable_Level_1?, Variable_Level_2?, Variable_Level_3?, Detailed_Variable?)>
<!ELEMENT Category (#PCDATA)>
<!ELEMENT Topic (#PCDATA)>
<!ELEMENT Term (#PCDATA)>
<!ELEMENT Variable_Level_1 (#PCDATA)>
<!ELEMENT Variable_Level_2 (#PCDATA)>
<!ELEMENT Variable_Level_3 (#PCDATA)>
<!ELEMENT Detailed_Variable (#PCDATA)>

<!-- ISO_Topic_Category=================================================== -->

<!ELEMENT ISO_Topic_Category (#PCDATA)>

<!-- Keywords ==================================================== -->

<!ELEMENT Keyword (#PCDATA)>

<!-- Sensor Name ================================================= -->

<!ELEMENT Sensor_Name (Short_Name, Long_Name?)>
<!ELEMENT Short_Name (#PCDATA)>
<!ELEMENT Long_Name (#PCDATA)>

<!-- Source Name ================================================= -->

<!ELEMENT Source_Name (Short_Name, Long_Name?)>

<!-- Temporal Coverage =========================================== -->

<!ELEMENT Temporal_Coverage (Start_Date?, Stop_Date?)>
<!ELEMENT Start_Date (#PCDATA)>
<!ELEMENT Stop_Date (#PCDATA)>

<!-- Paleo Temporal Coverage ===================================== -->

<!ELEMENT Paleo_Temporal_Coverage 
  (Paleo_Start_Date?, Paleo_Stop_Date?, Chronostratigraphic_Unit*)>

<!ELEMENT Paleo_Start_Date (#PCDATA)>
<!ELEMENT Paleo_Stop_Date (#PCDATA)>
<!ELEMENT Chronostratigraphic_Unit (Eon, Era?, Period?, Epoch?, Stage?, Detailed_Classification?)>
<!ELEMENT Eon (#PCDATA)>
<!ELEMENT Era (#PCDATA)>
<!ELEMENT Period (#PCDATA)>
<!ELEMENT Epoch (#PCDATA)>
<!ELEMENT Stage (#PCDATA)>
<!ELEMENT Detailed_Classification (#PCDATA)>

<!-- Data Set Progress =========================================== -->

<!ELEMENT Data_Set_Progress (#PCDATA)>

<!-- Spatial Coverage ============================================ -->

<!ELEMENT Spatial_Coverage (
  Southernmost_Latitude?, Northernmost_Latitude?,
  Westernmost_Longitude?, Easternmost_Longitude?, 
  Minimum_Altitude?, Maximum_Altitude?,
  Minimum_Depth?, Maximum_Depth? )
>

<!ELEMENT Southernmost_Latitude (#PCDATA) >
<!ELEMENT Northernmost_Latitude (#PCDATA) > 
<!ELEMENT Westernmost_Longitude (#PCDATA) > 
<!ELEMENT Easternmost_Longitude (#PCDATA) > 
<!ELEMENT Minimum_Altitude (#PCDATA) >
<!ELEMENT Maximum_Altitude (#PCDATA) > 
<!ELEMENT Minimum_Depth (#PCDATA) > 
<!ELEMENT Maximum_Depth (#PCDATA)>

<!-- Location ==================================================== -->

<!ELEMENT Location (Location_Category, Location_Type?, Location_Subregion1?, Location_Subregion2?, Location_Subregion3?, Detailed_Location?)>

<!ELEMENT Location_Category (#PCDATA)>
<!ELEMENT Location_Type (#PCDATA)>
<!ELEMENT Location_Subregion1 (#PCDATA)>
<!ELEMENT Location_Subregion2 (#PCDATA)>
<!ELEMENT Location_Subregion3 (#PCDATA)>
<!ELEMENT Detailed_Location (#PCDATA)>

<!-- Data Resolution ============================================= -->

<!ELEMENT Data_Resolution (
  Latitude_Resolution?, Longitude_Resolution?, Horizontal_Resolution_Range?, Vertical_Resolution?, Vertical_Resolution_Range?, Temporal_Resolution?, Temporal_Resolution_Range? )
>

<!ELEMENT Latitude_Resolution (#PCDATA) >
<!ELEMENT Longitude_Resolution (#PCDATA) >
<!ELEMENT Horizontal_Resolution_Range (#PCDATA) >
<!ELEMENT Vertical_Resolution (#PCDATA) >
<!ELEMENT Vertical_Resolution_Range (#PCDATA) >
<!ELEMENT Temporal_Resolution (#PCDATA) >
<!ELEMENT Temporal_Resolution_Range (#PCDATA) >

<!-- Project ===================================================== -->

<!ELEMENT Project (Short_Name, Long_Name?)>

<!-- Quality ===================================================== -->

<!ELEMENT Quality (#PCDATA)>

<!-- Access Constraints ========================================== -->

<!ELEMENT Access_Constraints (#PCDATA)>

<!-- Use Constraints ============================================= -->

<!ELEMENT Use_Constraints (#PCDATA)>

<!-- Data Set Language ============================================ -->

<!ELEMENT Data_Set_Language (#PCDATA)>

<!-- Originating Center ========================================== -->

<!ELEMENT Originating_Center (#PCDATA)>

<!-- Data Center ================================================= -->

<!ELEMENT Data_Center (
  Data_Center_Name, Data_Center_URL?,Data_Set_ID*, Personnel+ )
>
<!ELEMENT Data_Center_Name (Short_Name, Long_Name?)>
<!ELEMENT Data_Center_URL (#PCDATA)>
<!ELEMENT Data_Set_ID (#PCDATA)>

<!-- Distribution ================================================ -->

<!ELEMENT Distribution (Distribution_Media?, Distribution_Size?, 
  Distribution_Format?, Fees?)>

<!ELEMENT Distribution_Media (#PCDATA)>
<!ELEMENT Distribution_Size (#PCDATA)>
<!ELEMENT Distribution_Format (#PCDATA)>
<!ELEMENT Fees (#PCDATA)>

<!-- Multimedia Sample =========================================== -->

<!ELEMENT Multimedia_Sample ( File?, URL?, Format?, Caption?, Description?)>

<!ELEMENT File (#PCDATA)>
<!ELEMENT Format (#PCDATA)>
<!ELEMENT Caption (#PCDATA)>
<!ELEMENT Description (#PCDATA)>

<!-- Reference =================================================== -->

<!ELEMENT Reference (#PCDATA)>

<!-- Summary ===================================================== -->

<!ELEMENT Summary (#PCDATA)>

<!-- Related URL ================================================= -->

<!ELEMENT Related_URL (URL_Content_Type?, URL+, Description?)>

<!ELEMENT URL_Content_Type (Type, Subtype?)>
<!ELEMENT Type (#PCDATA)>
<!ELEMENT Subtype (#PCDATA)>

<!ELEMENT URL (#PCDATA)>

<!-- Parent_DIF ================================================== -->

<!ELEMENT Parent_DIF (#PCDATA)>

<!-- IDN Node ==================================================== -->

<!ELEMENT IDN_Node (Short_Name, Long_Name?)>

<!-- Originating Metadata Node =================================== -->

<!ELEMENT Originating_Metadata_Node (#PCDATA)>

<!-- Metadata Name =================================== -->

<!ELEMENT Metadata_Name (#PCDATA)>


<!-- Metadata Version =================================== -->

<!ELEMENT Metadata_Version (#PCDATA)>

<!-- DIF Creation Date =========================================== -->

<!ELEMENT DIF_Creation_Date (#PCDATA)>

<!-- Last DIF Revision Date ====================================== -->

<!ELEMENT Last_DIF_Revision_Date (#PCDATA)>

<!-- DIF Revision History ======================================== -->

<!ELEMENT DIF_Revision_History (#PCDATA)>

<!-- Future DIF Review Date ====================================== -->

<!ELEMENT Future_DIF_Review_Date (#PCDATA)>

<!-- Public/Private Flag ====================================== -->

<!ELEMENT Public (#PCDATA)>