1 Rub. Control Mark StudyThis topic has 1 reply, 2 voices, and was last updated 1 year, 4 months ago by Ged Seiflow.Viewing 1 reply threadAuthorPosts 22 November 2020 at 11:02 pm #30923 A SafonoffParticipantSeveral catalogues list Control Marks in the sheet margins for the 1910 1 Rub. Issue –1. Control letters of “crisscrossing Vs”2. 1 to 3 Control Lines of various colours printed printed in the vertical margins Is anyone aware of the existence any in depth Studies or Documentations of these Control Marks? 8 January 2021 at 5:56 pm #31102 Ged SeiflowParticipantYou might want to look at Fomin’s Katalog-Handbuch (1997) page 46 onwards. This might be sufficient for your needs. AuthorPostsViewing 1 reply threadYou must be logged in to reply to this topic.Log In Username: Password: Keep me signed in Log In