Add _dictionary.licence attribute

ddl.dic

@@ -11,10 +11,11 @@ data_DDL_DIC
     _dictionary.title             DDL_DIC
     _dictionary.class             Reference
     _dictionary.version           4.2.0
-    _dictionary.date              2026-01-20
+    _dictionary.date              2026-02-24
     _dictionary.uri
         https://raw.githubusercontent.com/COMCIFS/DDLm/main/ddl.dic
     _dictionary.ddl_conformance   4.2.0
+    _dictionary.licensing_SPDX    CC-BY-4.0
     _dictionary.namespace         DDLm
     _description.text
 ;
@@ -661,6 +662,62 @@ save_dictionary.formalism
 
 save_
 
+save_dictionary.licensing_details
+
+    _definition.id                '_dictionary.licensing_details'
+    _definition.class             Attribute
+    _definition.update            2026-02-24
+    _description.text
+;
+    Details about the licence or licences under which this dictionary
+    is distributed. _dictionary.licensing_SPDX should be used where
+    the licence is included in the SPDX list.
+;
+
+    _name.category_id             dictionary
+    _name.object_id               licensing_details
+    _type.purpose                 Audit
+    _type.source                  Assigned
+    _type.container               Single
+    _type.contents                Text
+
+save_
+
+save_dictionary.licensing_spdx
+
+    _definition.id                '_dictionary.licensing_SPDX'
+    _definition.class             Attribute
+    _definition.update            2026-02-24
+    _description.text
+;
+    The licence or licences under which this dictionary is distributed,
+    specified using an SPDX license expression
+    (https://spdx.dev/learn/handling-license-info/). If the licence is not
+    listed in the curated SPDX list (https://spdx.org/licenses/) then the
+    full text of the licence should be included in
+    _dictionary.licensing_details. Registration with
+    the SPDX project and use of an SPDX license expression is strongly
+    encouraged.
+
+    Ref: International Organization for Standardization (2021). ISO/IEC
+    5962:2021. Information technology — SPDX® Specification V2.2.1. Geneva:
+    International Organization for Standardization.
+;
+
+    _name.category_id             dictionary
+    _name.object_id               licensing_spdx
+    _type.purpose                 Audit
+    _type.source                  Assigned
+    _type.container               Single
+    _type.contents                Text
+
+    loop_
+      _description_example.case
+         'CC-BY-4.0'
+         'CC-BY-4.0 OR CC0-1.0+'
+
+save_
+
 save_dictionary.namespace
 
     _definition.id                '_dictionary.namespace'
@@ -2598,7 +2655,8 @@ save_
                                    '_dictionary_audit.version'
                                    '_dictionary_audit.date'
                                    '_dictionary_audit.revision'
-                                   '_dictionary.doi']
+                                   '_dictionary.doi'
+                                   '_dictionary.licensing_spdx']
          Dictionary  Prohibited   [ALIAS  CATEGORY_KEY  DEFINITION
                                    DESCRIPTION_EXAMPLE  ENUMERATION  IMPORT
                                    METHOD  NAME  TYPE  UNITS]
@@ -3115,7 +3173,7 @@ save_
        by explicitly specifying that it adheres to the formal grammar
        provided in SemVer version 2.0.0.
 ;
-         4.2.0                    2026-01-20
+         4.2.0                    2026-02-24
 ;
        # Please update the date above and describe the change below until
        # ready for the next release
@@ -3170,6 +3228,8 @@ save_
 
        Changed _dictionary.namespace attribute from 'DdlDic' to 'DDLm'.
 
+       Added dictionary licensing attributes.
+
        Specified that the DEFINITION_REPLACED category may be used to deprecate
        categories, added usage examples.
 ;