I am really grateful to everybody who helped with Domine non sum dignus.It seems most obvious, that the phrase was used "as a kind of punctuation mark for the self-concious awareness" as Dr. Zimmermann suggests. It often occurs at the end of the letters and on the back sides of the letters exchanged by the dominican monks and even seems to be a kind of a pass-word among the circle of a certain group of friends. The same phrase is also written by an anonimous monk of the same Tallinn Dominican monastery on the back cover of a printen Legenda Aurea (Nuernberg, Anton Koberger 1482) amongst some Estonian words. These Estonian words are almost the first known written record in this language (except two words in the chronicle of Henricus de Lettis at the beginning of the 13-th c.). Normally the written vernacular in medieval Livonia was Low Middle German. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%