Support for "Ideographic Variation Selectors" requires advanced unicode
processing. Many of the older document formats are not able to e.g. support
UTF-16  surrogate pairs. Exporting via the traditional way of using encoding
converters results in undefined/questionmark substitution for the VS chars. The
undefined or questionmark substitution char causes more harm than benefit, so
the VS chars should be ignored in these cases. The involved file-export filters
have to be identified and be changed appropriately.