 "Strict" Knittelvers has eight or nine syllables on each line, whereas "free" Knittelvers can use more or fewer.It may be considered a form of doggerel and is sometimes called "Knüttelvers" () because of its rhythm.In German, this form of poetry was popular during the 15th and 16th centuries but rejected in the 17th before being brought back into use by Johann Christoph Gottsched in the 18th century.