By chance I found a Zenith "Tarif list" from 1914/15 for Austria- Hungary. It's very interesting about early Zenith "Chronometers". This was the aera when you can test for money in the Observatory your lever watch and take part on competitions but it wasn't a offically appointed chronometer. The term chronometer was connected to the design of the escapement as the base of the definition until 1925 on the one side. On the other side the term was used on several watch dials from a lot of producers and a bright range of movement qualities without any definition. Only since 1925 when the definition changed in switzerland and based now on the precision of a watch, universal standards, were introduced to define "Chronometer accuracy" and measurement conditions for Chronometers Class 1, 2 and 3. (These have since been adapted to the technical progress of the time again and again)
We see, that you can buy "Chronometer" with bulletin de marche and lever escapement before these days:
Surprisingly for a " Zenith Chronometer with a bulletin de marche of a appointed observatory" (Translation of the title) they take an add on from 15 - 300 Kronen on top to the standard price of the watch those days. ( For comparison: Within the same publicity a standard Zenith pocket watch in a normal simple silver case cost about 40 Kronen.)
I asked a chronometer specialist about this huge span. He explained to me that not even "Chronometer" was defined as well the scope of testing and, if desired adjustment and the observarory. The observatory did not have to be the public appointed institution like Neuchatel or Besancon. Likewise, major manufacturers as well as watchmaking schools have an observatory who created bulletin de marche. Therefore if you buy a pocket watch out of this aera chronometre or chronometer on the dial means nothing. If you're are lucky and a bulletin de marche still excist, read studious to understand what you've.
This is very new to me. If someone owns bulletins de marche, especially an inoffical swiss one, out of the aera before 1925, it would be gread if he post it here. I'm curious for any additional informations.