Not for points German to English Law/Patents Law (general) possibly: passport or other formal registration terminology [?]

This abbreviation "Kenn." is what I would like explained and defined. I understand that "Nr." is an abbreviation for "Nummer"
(English: number). "Kenn. Nr." appears on the top line filled in on each of my late grandfather and grandmother's "Vermøgensverzeichnis" documents issued by the Nazi regime when my grandfather and grandmother were deported from Vienna, on August 27, 1942 to Theresienstadt, and on April 9, 1942, to Izbica, Poland, respectively.
On each of my grandparent's documents, "Kenn. Nr. " is printed at the end of the line, in which each of their names are filled in. My grandfather's "Kenn. Nr." is filled in as "C oo923o." My grandmother's "Kenn. Nr. is filled in as " stls." which I understand is the abbreviation for "Staatenlos" - (English: stateless).