For unknow individuals surname (not forename), I so far, entered "???" as surname. I've got a small tree but already 6 persons are named ???. The funny thing is that "???" family is within the list of the .htm files generated metanames.
I suggest Genopro to implement a check/ignore routine for these unknown names (to not appear in the metanames list) bearing in mind that some other users may use a different approach for naming their unknown persons.
or Genepro to explain what is the best way to deal with unknown surnames. I'll be glad to modify my tree accordingly. Thanks.