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%lang-source-atts; Multi-lingual Language Source Attributes

Parameter entity collecting the two attributes @lang-source and @lang-source-custom, for easy access and removal together.
Declaration
<!ENTITY % lang-source-atts
            "lang-source 
                        (%lang-source-types;)             #IMPLIED
             lang-source-custom 
                        CDATA                             #IMPLIED"  >
Expanded Declaration

lang-source (author | editor | translator | machine | custom) #IMPLIED lang-source-custom CDATA #IMPLIED