<!--
  * dtd/filterConfig.dtd
  *
  * Copyright (c) 2014-2021 Simon Fraser University
  * Copyright (c) 2000-2021 John Willinsky
  * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
  *
  * DTD for filter definitions.
  -->

<!--
  * filterConfig - container for filter configuration
  -->
<!ELEMENT filterConfig (filterGroups?, filters?)>

<!--
  * filterGroups - a collection of filterGroup elements (see there)
  -->
<!ELEMENT filterGroups (filterGroup+)>

<!--
  * filterGroup - a group of transformations with a common semantic and common input/output types.
  *
  * symbolic: a unique symbolic name for the group, see FilterGroup for more information on the nomenclature.
  * displayName: a translation key that points to a short label for the filter.
  * description: a translation key that points to a description of the filter.
  * inputType: a codified input type (see TypeDescription and its sub-classes for further information)
  * outputType: a codified output type (see TypeDescription and its sub-classes for further information)
  -->
<!ELEMENT filterGroup EMPTY>
	<!ATTLIST filterGroup
		symbolic CDATA #REQUIRED
		displayName CDATA #REQUIRED
		description CDATA #REQUIRED
		inputType CDATA #REQUIRED
		outputType CDATA #REQUIRED>


<!--
  * filters - a collection of filter elements (see there)
  -->
<!ELEMENT filters (filter+)>

<!--
  * filter - a transformation to be registered with the filter registry.
  *   NB: Only composite filters can have nested filters (see CompositeFilter).
  *
  * class: the filter class
  * inGroup: a symbolic group name (see filterGroup above)
  * isTemplate: whether this is a template for other transformations or a transformation itself.
  -->
<!ELEMENT filter (setting*, filter*)*>
	<!ATTLIST filter
		class CDATA #REQUIRED
		inGroup CDATA #REQUIRED
		isTemplate (0|1) #REQUIRED>

<!--
  * setting - a filter parameter (see FilterSetting class for details).
  *   similar to pluginSettings.dtd, can be extended to arrays/objects
  *   in the same way if required
  *
  * type: the type of the setting (string, integer, boolean, object/array or constant),
  *   NB: const is an additional type not present in pluginSettings.dtd
  *   which can be used to refer to a defined constant.
  -->
<!ELEMENT setting (name, value)>
<!ATTLIST setting type (int|string|bool|object|const) #REQUIRED>
<!ELEMENT name (#PCDATA)>
<!ELEMENT value (#PCDATA | array)*>
<!ELEMENT element (#PCDATA | array)*>
<!ATTLIST element key CDATA #IMPLIED>
<!ELEMENT array (element+)>