olemus
füüsilise dokumendi turvaelement
= security element of a physical document

näiteid
https://stuff.mit.edu/people/stransky/stamps/alburgh_abg_passport_stamp.jpg

http://www.acrosscontinents.org/wp-content/uploads/2011/06/Australia-Immigration-entry-stamp-17-Jun-11.jpg

https://duckduckgo.com/?q=oval+stamp&t=h_&iax=images&ia=images