Project note for work package 10 “Wörterbuchinhalte / Dictionary” produced in the DGS-Korpus project. These Project Notes are part of the lexicographic manual for the dictionary. They cover the step of lemma establishment for the dictionary entries, which are made available online to the interested public as pre-release entries starting in 2020. In these Project Notes the criteria used for deciding what comprises a sign in the lexicographic sense and therefore is to be included into one dictionary entry are established and explained. These criteria include systematic-linguistic but also practice-oriented and pragmatic aspects. The criteria are phrased by the way of lemmatizing rules. Starting point of our considerations is the manual part of a sign, consequently a sign can be combined with different mouthings within one entry. A sign in actual use is often realized with different (word, i.e. sign) forms, the sum of which we call the range of the sign's forms. The lexicographic description in the entry aims to give a summarizing account of the lemma sign as adequately as possible considering the observed form realizations and textual meanings. Different lemma signs are to be described in separate entries. The lemma establishment decisions are made on basis of the data as they are observed in iLex, the annotational database of the DGS-Korpus project at the time of entry preparation. In practice this means that for the lemma establishment it is to be decided which types and subtypes are to be considered realizations of the lemma signs and therefore to be described in one entry and which are to be excluded and described in another entry.