We assume that the A mark refers to the R.H. minim, which results from the unquestionable notation of the three following, analogous bars. Therefore, it is a long accent, which is also confirmed by the evident accents in the next bars. In GE (→FE,EE,IE), although the position of the mark also points to the R.H., its length was adjusted to the L.H. triplet, as a result of which it looks more like a 
hairpin.
Compare the passage in the sources »
category imprint: Graphic ambiguousness; Differences between sources
issues: Long accents
notation: Articulation, Accents, Hairpins