We often get so caught up in narrow, technical discussion that the big picture is lost in a sea of words.
The art that we call Kunst des Fechtens begins with Johannes Liechtenauer, who was the Grand Master of the art. We read in Ms. 3227a that he didn't invent the art of fighting, but rather traveled in many lands seeking a perfect knowledge of it. We read in Cod.44.A.8 and elsewhere that he taught this knowledge using a long poem in three parts, which is called the Zettel. It was written in "obscure and cryptic words" intended to reveal the art to his students while hiding it from the uninitiated, and its 356 lines contain his teachings on lance, spear, sword, dagger, and wrestling.
Liechtenauer had a Fellowship with sixteen members, all masters in their own right. Of these sixteen, seven left teachings that survive today. Of these seven, two are known to have offered their own glosses and interpretations of the portion of Liechtenauer's Zettel on fencing with the long grip: Hans Seydenfaden von Erfurt and Sigmund [Schining] ain Ringeck. Likewise, two are known to have glossed the section on fencing with the short grip: Peter von Danzig zum Ingolstadt and (again) Sigmund ain Ringeck. (And of the sixteen, only Ringeck glossed the mounted portion of the Zettel.)
These glosses were never published nor widely disseminated, but were prized by later masters of the tradition. Captains of the Marxbrüder such as Peter Falkner and Antonius Rast owned copies, as well as such Freifechter as Lienhart Zollinger and Joachim Meyer. The tradition is dead now but the glosses survive, and through them we revive the art.
The only known copy of Peter von Danzig's gloss seems to date to 1452, and he may possibly have still been alive at the time.
No contemporary copy of the teachings of Seydenfaden or Ringeck exists, let alone one written in their own hands. From the 15th century we have only fragments: illustrations of Seydenfaden's plays in the Cluny Fechtbuch (1490s); nine paragraphs of Ringeck's gloss in Codex Speyer (1491). All other recordings that we have of them come from the 16th century. The earliest substantial copies of Ringeck's gloss are in Dresden (1504-1519) and Glasgow (1508). The only known textual record of Seydenfaden's teachings is in Augsburg (1539), quoted by a still later master named Hans Medel von Salzburg. Though these copies are quite late for a tradition founded in the early 1400s, we have no choice other than to treat them as faithful renderings.
Apart from these, there are a few other glosses from anonymous writers, referred to by nicknames such as Pseudo-Peter von Danzig, Jud Lew, and Pseudo-Hans Döbringer. These cover some or all of Liechtenauer's Zettel, but without knowing their authors, their authority is based on how closely they align with those of known masters.
Most KdF schools seek to cleave closely to glosses, but the masters themselves were not always in agreement about the meaning of Liechtenauer's verses. There are three identifiable lines of teaching that run from the Fellowship of Liechtenauer: that of Ringeck, which may be said to include the very similar anonymous glosses of Pseudo-Danzig and Jud Lew; that of Seydenfaden, which may be said to include the gloss of Hans Medel as well as the similar anonymous gloss of Pseudo-Döbringer; and that of Stettner, another master of the Fellowship whose student Paulus Kal produced an illustrated version of portions of Liechtenauer's verse.
Many of the plays and principles are the same across the separate lines, but there are clear and obvious disagreements. The names and positions of the four wards vary. Ringeck's Scalp-hew is a strike at the top of the head followed by a thrust to the face, whereas Seydenfaden's Scalp-hew is a strike at the top of the head followed by a rising cut to the right ear. Seydenfaden's Crown is when the sword is held cross-wise over the head (in the long or short sword position), whereas Ringeck's Crown is held with the cross and point directed upwards. There is not space here to compare Ringeck's gloss of the short sword to Danzig's, but that also reveals many differences in interpretation.
The ultimate truth of KdF is that there is no definitive interpretation of the Grand Master's teachings. His own students understood them differently, and Liechtenauer himself probably changed and evolved his teachings over the course of his life (which could be the reason for this difference in understanding). Thus, KdF schools and instructors may study multiple different lineages of KdF, but it's important to recognize the differences and learn from them, rather than attempting to mash them together into an undifferentiated mass.
Or they may choose to focus on one lineage only, with schools following Ringeck's Liechtenauer and schools following Seydenfaden's Liechtenauer coexisting, and in that way we might eventually arrive at a reflection of the diversity that was historical KdF.