In FE (→GE) the 
mark is placed only in b. 6, the first in a new line. However, the manner it was placed suggests that Chopin wanted it to begin earlier, probably similarly to the hairpin in b. 7-8. This is how it was understood in EE and this is the version we give in the main text. In turn, in GE the mark was considered to have been carelessly engraved, thus it was being gradually shortened and its starting point moved towards the 1st quaver in b. 6.
Compare the passage in the sources »
category imprint: Graphic ambiguousness; Differences between sources
issues: EE revisions, Inaccuracies in GE, Scope of dynamic hairpins, GE revisions
notation: Articulation, Accents, Hairpins