public ExternalIdentifiers getEntityIds(String ename) {
        EntityInfo entity = entityInfo.get(ename);
        return (entity == null) ? null : entity.ids;
    }
Return an external entity's identifiers.

@param ename
           The name of the external entity.
@return The entity's public identifier, system identifier, and base URI.
        Null if the entity was not declared as an external entity.
@see #getEntityType
src/nu/validator/gnu/xml/aelfred2/XmlParser.java