According to us, FE (→EE) positioning legatiss. under the 2nd quaver is either a result of an inaccurate reproduction of [A] or an example of an indication written within the scope of its validity. There are no doubts that legatissimo is to be applied from the beginning of the bar, together with the slur. In GE, the indication was moved to the beginning of the bar.
The simultaneous presence of a slur and legatiss. probably indicates the use of 'harmonic legato' (holding elements of a chord with fingers); in this case, it would most probably consist in holding the bottom dyads longer.
Compare the passage in the sources »
category imprint: Differences between sources
issues: GE revisions, Legato & slurs
notation: Verbal indications
