MDL XML Requirements

1. Overview:

This document defines the Digital Weather Markup Language (DWML). DWML is a new XML language which is being developed to initially support the exchange of the National Weather Service’s (NWS) National Digital Forecast Database (NDFD) data. However, the specification is being written with enough flexibility to accommodate other environmental science applications. Appendix E provides a definition of DWML types based on restrictions appropriate to NDFD data. Other sets of restrictions similar to those in Appendix E need to be established for other specific implementations.

1.1. DWML Requirements

This specification attempts to include requirements in the MDL NDFD XML Requirements document (Appendix A). The matrix in Appendix B indicates which design feature satisfies which requirement.

1.2. DWML Structure

The tree diagrams in Appendix C provide a graphical representation of how DWML elements and attributes relate to each other. These relationships in concert with the DWML type definitions in Appendix E form the basis for language validation.

1.3. Sample Document

In addition to providing a definition of the elements and their attributes, this specification provides sample DWML documents in Appendix D for the three products proposed in the NDFD XML Requirements document. Appendix D also includes the application of DWML elements to a Model Output Statistics (MOS) bulletin. The MOS bulletin example is a non-NDFD example and so it does not conform to the NDFD type definitions. The MOS bulletin example is provided merely to illustrate the flexibility of DWLM to handle other data sources.

2. DWML Data Element Nomenclature:

This specification uses the following approach to describing elements:

1) Element and attribute names are all lower case.

2) Element and attribute names use a hyphen (“-“) to separate multiple word names so as to improve readability (ex. <creation-date>). Attribute and element names avoid the use of abbreviations to enhance readability.

3) Within this document, child elements are nested in a sub-paragraph under their parents.

4) Attributes are also nested but do not have the angle brackets (“<>”) and are italicized.

5) The element’s and attribute’s type is provided in braces (“{}”). For more information on each type refer to Appendix E.

6) If the element can occur zero or more times, an asterisk (“*”) is placed after its name. See specification 5.2.1.5 for an example.

7) If the element occurs zero or one times, a question mark (“?”) follows its name. See specification 4.1.3 for an example.

8) If the element must appear at least once, a plus sign (“+”) trails its name. See specification 5.2.1 for an example.

9) Element names without a special trailing character must occur exactly once. Specification 3.1 provides an example of an element that is required exactly once.

10) Each DWML specification references the requirement that it is designed to meet. The requirement is positioned at the end of the specification and contained in parentheses. For example, specification 3.1 satisfies requirement 4.2.

11) The order of element descriptions in the paragraphs below is not significant. Any required ordering of elements is specified in the tree diagrams found in Appendix C and type definitions in Appendix E.

3. Framework Elements:

3.1. <dwml> Element

The <dwml> element {dw:dwmlType}: The root element for DWML (R4.2).

3.1.1. version Attribute

The version attribute {xsd:string} indicates which version of DWML the instance contains (R2.1.3).

3.2. <head> Element

The <head> element {dw:headType} contains the metadata for the DWML instance. See section 4 for elements found in the <head> element (R4.2).

3.3. <data> Element

The <data> element {dw:dataType} contains the environmental data. See section 5 for child elements of the <data> element (R4.2 and R2.2).

4. DWML Metadata Elements

DWML metadata provides information about the DWML product and the data it contains. These elements are children of the <head> element.

4.1. <product> Element

The <product> element {dw:productType} holds meta information about the product.

4.1.1. concise-name Attribute

The concise-name attribute {dw:concise-nameType} represents a name or code that describes this product. The concise-nameType will have a list of names that is extensible to support secondary developer additions. Sample values include “glance”, “digital-tabular”, “digital-zone” (Derived From R2.1.1).

4.1.2. srsName Attribute

The srsName attribute {dw:srsNameType} communicates the spatial reference system used by NDFD. The NDFD spatial reference system is the “WGS 1984”.

4.1.3. operational-mode Attribute

The operational-mode attribute {dw:operational-modeType} defines the status of the product. Applications can review the content of this element to determine if they should perform further processing. Sample values include “test”, “developmental”, “experimental”, and “official” product. (R2.1.4)

4.1.3.1. Test Product

The “test” product indicates that this is an instance of an existing DWML product that contains some change being evaluated by a DWML development team. Users will typically not process this product (R2.1.4.1).

4.1.3.2. Developmental Product

The “developmental” product represents a new product that is not yet ready for public evaluation or use (R2.1.4.2).

4.1.3.3. Experimental Product

This product is available for testing and evaluation for a specified, limited time period for the explicit purpose of obtaining customer feedback. (R2.1.4.3).

4.1.3.4. Official Product

The “official” product identifies an instance of an established DWML product. This DWML instance is part of the approved product suite available from the NWS (R2.1.4.4).

4.1.4. <title> Element

The <title> element {xsd:string} [?] provides a concise summarization of what this DWML product contains (R2.1.1).

4.1.5. <field> Element

The <field> Element {dw:fieldType} specifies the general area within the environmental sciences that the data contained in the DWML instance is from. Example values include “meteorological”, “hydrological”, “oceanographical”, “land surface”, and “space” (R2.1.5).

4.1.6. <category> Element

The <category> Element {dw:categoryType} [?] defines the specific category that the product belongs to. Example values include “observation”, “forecast”, “analysis”, and “statistic” (R2.1.6).

4.1.7. <creation-date> Element

The <creation-date> Element {xsd:creation-dateType} contains the date and time that the product was prepared (R2.1.2).

4.1.7.1. refresh-frequency Attribute

The refresh-frequency attribute {xsd:duration} is used by the production center to help users know how often to return for updated data. In the case of the NDFD, the data is updated on an as needed basis. As a result the frequency provided may not always ensure users update as soon as new data is available. The frequency will also not guarantee that that when updates are done that the retrieved data is new. Still, the suggested refresh frequency will help well mannered users know what the provider believes is a reasonable time between repeated accesses of the system (R2.1.14).

4.2. <source> Element

The <source> Element {dw:sourceType} [?] holds information about the product’s source and links to credit and disclaimer information.

4.2.1. <more-information> Element

The <more-information> element {xsd:anyURI} is a link to the web page of the forecast’s source or a more complete forecast (R2.1.13).

4.2.2. <production-center> Element

The <production-center> element {xsd:production-centerType} [?] identifies which organization creates the product (R2.1.7).

4.2.2.1. <sub-center> Element

The <sub-center> element {xsd:string} [?] is the part of the production center that prepared the product (R2.1.8).

4.2.3. <disclaimer> Element

The <disclaimer> element {xsd:anyURI} [?] is the URL containing a disclaimer regarding the data (R2.1.9).

4.2.4. <credit> Element

The <credit> Element {xsd:anyURI} [?] is the URL used to credit the source of the data (R2.1.10).

4.2.5. <credit-logo> Element

The <credit-logo> element {xsd:anyURI} [?] is the image link used with the credit URL to acknowledge the data source (R.2.11).

4.2.6. <feedback> Element

The <feedback> Element {xsd:anyURI} [?] is a URL to a web page used to provide the production center comments on the product (R2.1.12).

5. DWML Data Elements

These elements hold the environmental data. They are children of the <data> element.(R2.2).

5.1. <location> Element

The <location> element {dw:locationType} [+]: Defines the location for the data contained in the element <data>. The element must contain exactly one of its child elements (R2.2.2).

5.1.1. <location-key> Element

The <location-key> element {dw:location-keyType} [?] is used to relate the location to its corresponding parameters (R2.2.2).

5.1.2. <point> Element

For information on the <point> element see Section 7.1

5.1.2.1. summarization Attribute

For information on the summarization attribute see Section 7.3.

5.1.3. <city> Element

The <city> element {dw:cityType} [?] contains the city name for which the data is valid (R2.2.2).

5.1.3.1. state Attribute

The state attribute {dw:stateType} holds the two digit abbreviation for the state that the city resides in (R2.2.2).

5.1.3.2. summarization Attribute

For information on the summarization attribute see Section 7.3.

5.1.4. <nws-zone> Element

The <nws-zone> element {dw:nws-zoneType} [?] contains the National Weather Service forecast zone name for which the data is valid (R2.2.2).

5.1.4.1. state Attribute

The state attribute {dw:stateType} holds the two digit abbreviation for the state that the city resides in (R2.2.2).

5.1.4.2. summarization Attribute

For information on the summarization attribute see Section 7.3.

5.1.5. <area> Element

The <area> element {dw:areaType} [?] is a geometrical shape may be used to define which grid points the data represents. The element must contain exactly one of its child elements (Derived from R2.2.1.5).

5.1.5.1. area-type Attribute

The area-type attribute {dw:area-typeType} defines the aerial shape being used. Permissible values include “circle” and “rectangle” (Derived from R2.2.1.5).

5.1.5.2. <circle> Element

The <circle> element {dw:circleType} [?] is a circular area about a grid point. The area can contain any number of grid points which are summarized.

5.1.6. <point> Element

For information on the <point> element see Section 7.1

5.1.6.1.1. <radius> Element

The <radius> element {dw:radiusType} is the distance from the center point of the circle to edge of the circular area (Derived from R2.2.1.5).

5.1.6.1.1.1. radius-units Attribute

The radius-units attribute {dw:radius-unitsType) is the units of the radius measurement. Example values include “statute miles” and “kilometers” (Derived from R2.2.1.5).

5.1.6.2. summarization Attribute

For information on the summarization attribute see Section 7.3.

5.1.6.3. <rectangle> Element

The <rectangle> element {dw:rectangleType} [?] is a rectangular area which is defined by four latitude and longitude pairs. The area can contain any number of grid points which are summarized.

5.1.7. <point> Element

For information on the <point> element see Section 7.1

5.1.8. <point> Element

For information on the <point> element see Section 7.1

5.1.9. <point> Element

For information on the <point> element see Section 7.1

5.1.10. <point> Element

For information on the <point> element see Section 7.1

5.1.10.1. summarization Attribute

For information on the summarization attribute see Section 7.3.

5.1.11. <height> Element

The <height> element {dw:heightType} [?] is the data point’s distance above/below some datum. If this element is not present, it is assumed that the data values are surface based (R2.2.2.3.1).

5.1.11.1. datum Attribute

The datum attribute {dw:datumType} is the reference for the height measurement. Example values include “surface” and “mean sea level” (R2.2.2.3.1.1).

5.1.11.2. height-units Attribute

The height-units attribute {dw:unitsType}represents the units of measure used for the height value. Example values include “feet” and “meters” (R2.2.2.3.1.2).

5.1.12. <level> Element

The <level> element {dw:levelType} [?] allows the data to be valid at some specific level. For example, within model data, a value may apply to a sigma level (R2.2.2.3.2).

5.1.12.1. vertical-coordinate Attribute

For information on the vertical-coordinate attribute see Section 7.2.

5.1.13. <layer> Element

The <layer> element {dw:layerType} [?] allows the data to be valid for some specific layer. For example, within model data, a value may be valid through a sigma layer (R2.2.2.3.3).

5.1.13.1. vertical-coordinate Attribute

For information on the vertical-coordinate attribute see Section 7.2.

5.2. <moreWeatherInformation> Element

The <moreWeatherInformation> element {xsd:anyURI} contains a link to the NDFD point-and-click forecast page for each set of user requested lat/lon pairs.

5.2.1. applicable-location Attribute

The applicable-location attribute {dw:applicable-locationType} [?] is used to relate the location to a particular list of parameters (R2.2.1). In this case it is the user requested point number.

5.3. <time-layout> Element

The <time-layout> element {dw:time-layoutType } [+] contains the start and stop valid times and any associated period names for the data. Since different environmental parameters have different time schemes (valid at different interval and available for different lengths of time into the future), there will be one <time-layout> element for each of these unique temporal configurations. Each data parameter will reference exactly one of these time layouts (R2.2.3).

5.3.1. time-coordinate Attribute

The time-coordinate attribute {dw:time-coordinateType} defines the time coordinate as either “local time” or “UTC” (R2.2.3.3).

5.3.1.1. summarization Attribute

For information on the summarization attribute see Section 7.3.

5.3.2. <layout-key> Element

The <layout-key> element {dw:layout-keyType} contains the key (k-p24h-n7-1) used to associated this time layout with a particular parameter element (R2.2.3). The key is derived using the following convention:

1) “k” stands for key.

2) “p24h” implies a data period length of 24 hours.

3) “n7” means that the number of data times is 7.

4) “1” is a sequential number used to keep the layout keys unique.

The key should not be parsed to derive the period. This is because, the period length changes for some data type after day 3 and so period length implied by the key name only applies to the early times.

5.3.3. <start-valid-time> Element

The <start-valid-time> element {dw:start-valid-timeType} [+] is the start time of the period of time for which the data is valid (R2.2.3.1).

5.3.3.1.1. period-name Attribute

The period-name attribute {xsd:string} [?] contains the name associated with this time interval (ex. TODAY) (R2.2.3.4).

5.3.4. <end-valid-time> Element

The <end-valid-time> element {xsd:dateTime} [*]: The end time of the period of time for which the data is valid. The absence of this attribute indicates that the element is valid at a specific time (R2.2.3.2).

5.4. <parameters> Element

The <parameters> element {dw:parametersType} [+] holds the environmental data (R2.2.1).

5.4.1. applicable-location Attribute

The applicable-location attribute {dw:applicable-locationType} [?] is used to relate the location to a particular list of parameters (R2.2.1).

5.4.2. <temperature> Element

The <temperature> Element {dw:temperatureType} [*] is a container for temperature data (R2.2.1).

5.4.2.1. type Attribute

The type Attribute {dw:typeType} specifies the type of temperature. Example values include “maximum”, “minimum”, “temperature”, “dew point”, “heat index”, “wind chill” (R2.2.1.1).

5.4.2.2. units Attribute

The units attribute {dw:unitsType} defines the units of the temperature value. Example values include “F”, “C”, and “K”. The default value is “F” (R2.2.1.3).

5.4.2.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.2.4. <value> Element

The <value> element {dw:valueType} [+]: The temperature value reported to the nearest whole degree. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.2.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a temperature range (R2.2.1).

5.4.2.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a temperature range (R2.2.1).

5.4.2.5. <valueWithUncertainty> Element

The <valueWithUncertainty> element {dw: valueWithUncertaintyType} [+]: Element containing a <value> element and an <uncertainty> element. Represents a value like 75°F + or minus 1.5°F. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.2.5.1. <value> Element

The <value> element {dw:valueType} [+]: The temperature value reported to the nearest whole degree. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.2.5.1.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a temperature range (R2.2.1).

5.4.2.5.1.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a temperature range (R2.2.1).

5.4.2.5.2. <uncertainty> Element

Specifies the uncertainty {dw: uncertaintyType} [+] associated with the accompanying value.

5.4.2.5.2.1. type Attribute

The type Attribute {dw:uncertaintyTypeType} specifies the type of uncertainty. Example values include “analysis error” (R2.2.1.1).

5.4.2.5.2.2. <error> Element

The <error> element {errorType} [?] holds an uncertainty value characterized as an error.

5.4.2.5.2.2.1. qualifier Attribute

The qualifier attribute {dw:qualifierType} [?] is use to indicate how the error is applied. For example, a qualifier set to a value of “+/-“, indicating the error is to be added and subtracted from the base value to determine the range of values.

5.4.2.6. <name> Element

The <name> element {xsd:string} [?]: The name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.2.7. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.2.8. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.3. <precipitation> Element

The <precipitation> element {dw:precipitationType} [*] is a container for the precipitation values (R2.2.1).

5.4.3.1. type Attribute

The type Attribute {dw:typeType} specifies the type of precipitation parameter. Example values include “liquid” and “snow” (R2.2.1.1).

5.4.3.2. units Attribute

The units attribute {dw:unitsType} defines the units of the precipitation value. Example values include “inches” and “millimeters”. The default value is “inches” (R2.2.1.3).

5.4.3.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.3.4. <value> Element

The <value> element {dw:valueType} [+]: The precipitation type parameter’s value to the nearest integer value. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.3.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a precipitation range (R2.2.1).

5.4.3.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a precipitation range (R2.2.1).

5.4.3.5. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.3.6. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.3.7. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.4. <probability-of-precipitation> Element

The <probability-of-precipitation> element {dw:probability-of-precipitationType} [*] is a container for the probability of precipitation (POP) values (R2.2.1).

5.4.4.1. type Attribute

The type Attribute {dw:typeType} specifies the type of POP parameter. Example values include “12 hour” and “floating”. Default value is “12 hour” (R2.2.1.1).

5.4.4.2. units Attribute

The units attribute {dw:unitsType} defines the units of the POP value. Example values include “percent” (R2.2.1.3).

5.4.4.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.4.4. <value> Element

The <value> element {dw:valueType} [+]: The POP value to the nearest integer value. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.4.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a probability of POP range (R2.2.1).

5.4.4.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a POP range (R2.2.1).

5.4.4.5. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.4.6. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.4.7. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.5. <convective-hazard> Element

The <convective-hazard> element {dw:convective-hazardType} [*] is a container for the convective hazard values like hazard outlook, tornadoes, hail, severe thunderstorms from the Storm Prediction Center (R2.2.1).

5.4.5.1. type Attribute

The type Attribute {dw:typeType} specifies the type of convective hazard parameter. Example values include “outlook”, “tornadoes”, “hail”, “damaging thunderstorm wind” “extreme tornadoes”, “extreme hail”, “extreme thunderstorm winds”, “severe thunderstorms” and “extreme severe thunderstorms”. (R2.2.1.1).

5.4.5.2. units Attribute

The units attribute {dw:unitsType} defines the units of the convective hazard value. Example values include “percent” (R2.2.1.3).

5.4.5.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.5.4. <value> Element

The <value> element {dw:valueType} [+]: The convective hazard value to the nearest integer value. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.5.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a probability of convective hazard range (R2.2.1).

5.4.5.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a convective hazard range (R2.2.1).

5.4.5.5. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.5.6. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.5.7. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.6. <wind-speed> Element

The <wind-speed> element {dw:wind-speedType} [*] is a container for the wind speed values (R2.2.1).

5.4.6.1. type Attribute

The type Attribute {dw:typeType} specifies the type of wind speed parameter. Example values include “sustained”, “cumulative34”, and “gust” (R2.2.1.1).

5.4.6.2. units Attribute

The units attribute {dw:unitsType} defines the units of the wind speed values. Example values include “knots”, “meters per second”, and “percent”. The default value is “knots”. NOTE: “percent” is used for probabilistic winds (R2.2.1.3).

5.4.6.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.6.4. <value> Element

The <value> element {dw:valueType} [+]: The wind speed value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.6.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a wind speed range (R2.2.1).

5.4.6.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a temperature range (R2.2.1).

5.4.6.5. <valueWithUncertainty> Element

The <valueWithUncertainty> element {dw: valueWithUncertaintyType} [+]: Element containing a <value> element and an <uncertainty> element. Represents a value like 10 kts + or minus 2.0 kts. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.6.5.1. <value> Element

The <value> element {dw:valueType} [+]: The temperature value reported to the nearest whole degree. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.6.5.1.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a temperature range (R2.2.1).

5.4.6.5.1.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a temperature range (R2.2.1).

5.4.6.5.2. <uncertainty> Element

Specifies the uncertainty {dw: uncertaintyType} [+] associated with the accompanying value.

5.4.6.5.2.1. type Attribute

The type Attribute {dw:uncertaintyTypeType} specifies the type of uncertainty. Example values include “analysis error” (R2.2.1.1).

5.4.6.5.2.2. <error> Element

The <error> element {errorType} [?] holds an uncertainty value characterized as an error.

5.4.6.5.2.2.1. qualifier Attribute

5.4.6.5.3. The qualifier attribute {dw:qualifierType} [?] is use to indicate how the error is applied. For example, a qualifier set to a value of “+/-“, indicating the error is to be added and subtracted from the base value to determine the range of values.

5.4.6.6. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.6.7. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.6.8. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.7. <direction> Element

The <direction> element {dw:directionType} [?] is a container for the direction values (R2.2.1).

5.4.7.1. type Attribute

The type Attribute {dw:typeType} specifies the type of wind direction. Example values include “wind” and “swell”. The default value is “wind” (R2.2.1.1).

5.4.7.2. units Attribute

The units attribute {dw:unitsType} defines the units of the wind direction values. Example values include “degrees true” (R2.2.1.3).

5.4.7.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.7.4. <value> Element

The <value> element {dw:valueType} [+]: The wind direction value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.7.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a wind direction range (R2.2.1).

5.4.7.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a wind direction range (R2.2.1).

5.4.7.5. <valueWithUncertainty> Element

The <valueWithUncertainty> element {dw: valueWithUncertaintyType} [+]: Element containing a <value> element and an <uncertainty> element. Represents a value like 270° + or minus 5.0°. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.7.5.1. <value> Element

The <value> element {dw:valueType} [+]: The temperature value reported to the nearest whole degree. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.7.5.1.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a temperature range (R2.2.1).

5.4.7.5.1.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a temperature range (R2.2.1).

5.4.7.5.2. <uncertainty> Element

Specifies the uncertainty {dw:uncertaintyType} [+] associated with the accompanying value.

5.4.7.5.2.1. type Attribute

The type Attribute {dw:uncertaintyTypeType} specifies the type of uncertainty. Example values include “analysis error” (R2.2.1.1).

5.4.7.5.2.2. <error> Element

The <error> element {errorType} [?] holds an uncertainty value characterized as an error.

5.4.7.5.2.2.1. qualifier Attribute

5.4.7.5.3. The qualifier attribute {dw:qualifierType} [?] is use to indicate how the error is applied. For example, a qualifier set to a value of “+/-“, indicating the error is to be added and subtracted from the base value to determine the range of values.

5.4.7.6. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.7.7. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.7.8. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.8. <cloud-amount> Element

The <cloud-amount> element {dw:cloud-amountType} [*] is a container for the cloud amount values (R2.2.1).

5.4.8.1. type Attribute

The type Attribute {dw:typeType} specifies the type of cloud amount values. Example values include “total” and “layered” (R2.2.1.1).

5.4.8.2. units Attribute

The units attribute {dw:unitsType} defines the units of the cloud amount values. Example values include “percent” and “8ths”. The default value is “percent” (R2.2.1.3).

5.4.8.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.8.4. <value> Element

The <value> element {dw:valueType} [+]: The cloud cover value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.8.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a range of cloud amount (R2.2.1).

5.4.8.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a range of cloud amount (R2.2.1).

5.4.8.5. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.8.6. <cloud-layer> Element

The <cloud-layer> element {dw:layerType} [?] is the layer containing the cloud amount. Example values include “high”, “middle”, and “low”. This element is not present when the type attribute is set to “total” (Derived from R2.2.1).

5.4.8.7. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.8.8. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.9. <weather> Element

The <weather> element {dw:weatherType} [?] is a container for the weather values (R2.2.1).

5.4.9.1. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.9.2. <weather-conditions> Element

The <weather-conditions> element {weather-conditionsType} [+] is a container for up to three weather values that are used to describe the weather conditions at a given time. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.9.3. <value> Element

The <value> element {dw:valueType} [* (max of 5)] hold the sensible weather information. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.9.3.1.1. coverage Attribute

The coverage attribute {dw:coverageType} [?] holds the weather coverage value. Valid values for the NDFD are contained in Appendix E, Table 3 (R2.2.1).

5.4.9.3.1.2. intensity Attribute

The intensity attribute {dw:intensityType} [?] holds the weather intensity. Valid values for the NDFD are contained in Appendix E, Table 4 (R2.2.1).

5.4.9.3.1.3. additive Attribute

The additive attribute {dw:additiveType} [?] dictates whether the following value element is combined using an “and” or an “or”. For example rain and snow vice rain or snow (R2.2.1).

5.4.9.3.1.4. qualifier Attribute

The qualifier attribute {dw:qualifierType} [?] is used to communicate a special aspect of the weather value. Valid values for the NDFD are contained in Appendix E, Table 6 (R2.2.1).

5.4.9.3.1.5. weather-type Attribute

The weather-type attribute {dw:weather-typeType} [?] captures the weather element being forecast. Valid values for the NDFD are contained in Appendix E, Table 5 (R2.2.1).

5.4.9.3.1.6. <visibility> Element

The <visibility> element {dw:visibilityType} [*] contains the weather visibility value (R2.2.1).

5.4.9.3.1.6.1. units Attribute

The units attribute {dw:unitsType} contains the units of the visibility value. Example values include “statute miles” and “meters” (R2.2.1).

5.4.9.4. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.9.5. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.9.6. weather-summary Attribute

The weather-summary Attribute {xsd:string} [?] is a short phrase (~2 words) used to summarize the weather conditions for that time. Example phrases include “partly cloudy” and “scattered thunderstorms” (R2.2.1).

5.4.10. <humidity> Element

The <humidity> Element {dw:humidityType} [?] is a container for humidity values (R2.2.1).

5.4.10.1. type Attribute

The type Attribute {dw:typeType} specifies the type of humidity. Example values include “relative” and “specific” (R2.2.1.1).

5.4.10.2. units Attribute

The units attribute {dw:unitsType} defines the units of the humidity values. Example values include “percent” and “kilogram/kilogram” (R2.2.1.3).

5.4.10.3. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.10.4. <value> Element

The <value> element {dw:valueType} [+]: The humidity value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.10.4.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a relative humidity range (R2.2.1).

5.4.10.4.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a relative humidity range (R2.2.1).

5.4.10.5. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.10.6. categorical-table Attribute

The categorical-table attribute {dw:categorical-tableType} [?] is the foreign key to a list of categories that define the meaning of the value (R2.2.1).

5.4.10.7. conversion-table Attribute

The conversion-table attribute {dw:conversion-tableType} [?] is the foreign key to a list of conversions tables that provide a equivalent value for the data (R2.2.1).

5.4.11. <conditions-icons> Element

The <conditions-icons> element {dw:conditions-iconsType} [?] holds a URL for a weather icon depicting the cloud and precipitation conditions. The icons will be consistent with other NWS forecast products (R5.1).

5.4.11.1. type Attribute

The type Attribute {dw:typeType} specifies the type of icons. Example values include “forecast-NWS” (R2.2.1.1).

5.4.11.2. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.11.3. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.11.4. <icon-link> Element

The <icon-link> element {xsd:anyURI} [+] contains the URL of the icon used to represent weather conditions (R5.1).

NOTE: The priority algorithm for icon determination can be found in Table 8–Table 11. In these tables, the nomenclature [20,30…90,100] indicates that one of the 2 digit values appear in the icon file name. For example, the rain icon could be ra20.jpg, ra30.jpg on up to ra100.jpg.

5.4.12. <wordedForecast> Element

The <wordedForecast> element {dw:wordedForecastType} [?] holds a text representation of the forecast for the indicated time period.

5.4.12.1. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.12.2. dataSource

Describes the data source used to create the worded forecast (examples include “NDFD Mosaic” or “Local NetCDF”, etc.).

5.4.12.3. wordGenerator

Specifies which algorithm was used to create the worded forecast (examples include “MarkMitchell”).

5.4.12.4. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.12.5. <text> Element

The <text> element {dw:textType} [+]: The worded forecast. Missing entries are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.13. <water-state> Element

The <water-state> Element {dw:water-stateType} [?] is a container for sea and wave information. The seas element will not be present when the waves or swell elements are used. The wave and swell can both appear or they may appear separately (R2.2.1).

5.4.13.1. time-layout Attribute

For information on the time-layout attribute see Section 7.4.

5.4.13.2. <seas> Element

The <seas> element {dw:seasType} [?] holds the height of the seas which is a combination of both wind waves and swell (R2.2.1).

5.4.13.3. type Attribute

The type Attribute {dw:typeType} specifies the type of seas. An example value includes “combined” (R2.2.1.1).

5.4.13.4. units Attribute

The units attribute {dw:unitsType} defines the units of the seas values. Example values include “feet” and “meters” (R2.2.1.3).

5.4.13.5. <value> Element

The <value> element {dw:valueType} [+]: The seas value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.13.5.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a sea height range (R2.2.1).

5.4.13.5.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a sea height range (R2.2.1).

5.4.13.6. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.13.7. <waves> Element

The <waves> element {dw:wavesType} [?] holds the height of waves generated by the local wind blowing (R2.2.1).

5.4.13.8. type Attribute

The type Attribute {dw:typeType} specifies the type of waves. An example value includes “wind” or “significant” (R2.2.1.1).

5.4.13.9. units Attribute

The units attribute {dw:unitsType} defines the units of the wave values. Example values include “feet” and “meters” (R2.2.1.3).

5.4.13.10. <value> Element

The <value> element {dw:valueType} [+]: The wave value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.13.10.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a wave height range (R2.2.1).

5.4.13.10.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a wave height range (R2.2.1).

5.4.13.10.2.1. period Attribute

The period attribute {xsd:nonNegativeIntegers} [?] holds the time, in seconds for the passage of successive wave crests (R2.2.1).

5.4.13.10.2.2. steepness Attribute

The steepness attribute {xsd:nonNegativeIntegers} [?] holds the Ratio of wave height to wavelength. Theoretical wave steepness maximum is around 1/10, after which the wave becomes unstable and breaks (R2.2.1).

5.4.13.11. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.13.12. <swell> Element

The <swell> element {dw:swellType} [?] holds the height of wind waves which have traveled beyond the wave generation region (R2.2.1).

5.4.13.13. type Attribute

The type Attribute {dw:typeType} specifies the type of swell. An example value includes “significant” (R2.2.1.1).

5.4.13.14. units Attribute

The units attribute {dw:unitsType} defines the units of the swell values. Example values include “feet” and “meters” (R2.2.1.3).

5.4.13.15. <value> Element

The <value> element {dw:valueType} [+] contains the swell value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.13.15.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a swell height range (R2.2.1).

5.4.13.15.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a swell height range (R2.2.1).

5.4.13.15.2.1. period Attribute

The period attribute {xsd:nonNegativeIntegers} [?] holds the time, in seconds for the passage of successive wave crests (R2.2.1).

5.4.13.15.2.2. steepness Attribute

5.4.13.16. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.13.16.1. <direction> Element

The <direction> element {dw:directionType} [+] is a container for the direction values (R2.2.1).

5.4.13.17. type Attribute

The type Attribute {dw:typeType} specifies the type of swell direction. Example values include “wind” and “swell”. The default value is “wind” (R2.2.1.1).

5.4.13.18. units Attribute

The units attribute {dw:unitsType} defines the units of the swell direction values. Example values include “degrees true” (R2.2.1.3).

5.4.13.19. <value> Element

The <value> element {dw:valueType} [+] holds the direction value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.13.19.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a swell direction range (R2.2.1).

5.4.13.19.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a swell direction range (R2.2.1).

5.4.13.20. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.4.13.21. ice-coverage Element

The ice-coverage element {dw:ice-coverageType} [?] holds the amount of ice on the water body (R2.2.1).

5.4.13.22. type Attribute

The type attribute {dw:typeType} specifies the type of ice coverage. An example value includes “total” (R2.2.1.1).

5.4.13.23. units Attribute

The units attribute {dw:unitsType} defines the units of the ice cverage values. Example values include “percent” (R2.2.1.3).

5.4.13.24. <value> Element

The <value> element {dw:valueType} [+]: The ice coverage value reported to the nearest integer. Missing values are represented by an empty element and xsi:nil=”true” (R2.2.1).

5.4.13.24.1. upper-range Attribute

The upper-range attribute {dw:upper-rangeType} [?] holds the value associated with the upper end of a ice coverage range (R2.2.1).

5.4.13.24.2. lower-range Attribute

The lower-range attribute {dw:lower-rangeType} [?] holds the value associated with the lower end of a ice coverage range (R2.2.1).

5.4.13.25. <name> Element

The <name> element {xsd:string} [?] is the name of this parameter. The name value can be used for display purposes (R2.2.1.2).

5.5. <categorical-definitions> Element

The <categorical-definitions> element {dw:categorical-definitionsType} [?] contains the definitions of categories found in parameter value elements (R2.2.1).

5.5.1. <categorical-table> Element

The <categorical-table> element {dw:categorical-table-elementType} [+] contains the categorical data (R2.2.1).

5.5.1.1. units Attribute

5.5.1.2. The units attribute {dw:unitsType} defines the units of the data in the categories (R2.2.1).

5.5.1.3. <categorical-key> Element

The <categorical-key> element {dw:categorical-keyType} is the primary key relating the data in the parameter element to a particular categorical table (R2.2.1).

5.5.1.4. <value> Element

The <value> element {dw:valueType} [+]: The value found in the data (R2.2.1).

5.5.1.4.1. category {xsd:string}: The category corresponding to the value (R2.2.1).

5.6. <conversion-definitions> Element

The <conversion-definitions> element {dw:conversion-definitionsType} [?] contains look-up tables used to relate numerical data to an equivalent value (R2.2.1).

5.6.1. <conversion-table> Element

The <conversion-table> element {dw:conversion-table-elementType} [+] holds the range of data associated with each equivalent value (R2.2.1).

5.6.1.1. <conversion-key> Element

The <conversion-key> element {dw:conversion-keyType} contains the primary key relating the data in the parameter element to a particular conversion table (R2.2.1).

5.6.1.2. <start-value> Element

The <start-value> element {dw:start-valueType} [+] is the starting value of the range of data for which the value is equivalent (R2.2.1).

5.6.1.3. <end-value> Element

The <end-value> element {dw:end-valueType} [+] is the ending value of the range of data for which the value is equivalent (R2.2.1).

5.6.1.4. <equivalent-value> Element

The <equivalent-value> element {xsd:string} [+] is the equivalent value of the data (R2.2.1).

6. Latitude and Longitude Lists

6.1. <latLonList> Element

The <latLonList> element {dw:latLonListType} [?] holds a list of latitude and longitude pairs that are contained in a subgrid. A latitude and longitude pair is composed of a latitude value followed by a comma followed by a longitude value (i.e. 38.98,-77.07). Each latitude and longitude pair is separated by a space (i.e. 33.869922,-80.080906 33.914765,-80.074936).

7. Common Element and Attribute Definitions

7.1. <point> Element

The <point> element {dw:pointType} [?] is the element used to define the grid point for which the data is valid (R2.2.2).

7.1.1. latitude Attribute

The latitude attribute {xsd:decimal} defines the latitude of the point where the data is valid (R2.2.2.2).

7.1.2. longitude Attribute

The longitude attribute {xsd:decimal} defines the latitude of the point where the data is valid (R2.2.2.2).

7.2. vertical-coordinate Attribute

The vertical-coordinate attribute {xsd:string} defines the data’s vertical position (R2.2.2.3).

7.3. summarization Attribute

The summarization attribute {dw:summarizationType} [?] indicates how a collection of grid point values is summarized into a single value. Example summarization types include “none”, “mean”, “median”, “mode”, “maximum”, “minimum”, “12hourly”, or “24hourly”. A value of “none” indicates that the values are valid at a single grid point or time (R2.2.1.5).

7.4. time-layout Attribute

The time-layout attribute {dw:time-layoutType} defines the key to the appropriate valid times and any relevant period name information (R2.2.3).

8. XML Considerations

8.1. Namespace

DWML will use the namespace http://www.nws.noaa.gov/mdl/ndfd/dwml.

8.2. Schema

DWML will use XML Schema to perform validity checking.

8.3. Character Set

DWML will use UTF-8 encoding.