&dAInv. 3, BWV 774, r.h.&d@  

SLUR plus MORDENT, m. 3, 45: In P 610, the slur both times 
appears connected to the mordent. This caused BG to interpret them 
as a single ornament, a "doppelt-cadence und mordent" from the 
"Explication". Neumann, p. 445-6, however, describes this 
combination as a "compound grace", termed a &dBport de voix et pince&d@, 
and considers it a written-out equivalent of the "Accent und 
Mordant" of the "Explication": the second eighth note, B4, is 
actually a long appogiatura to the following C#5, and the mordent 
should be performed, not on the beat of the C#5, but just before 
it, as a kind of "suffix" to the B4.  
  
W = LONG TRILL, m. 22: As in Inv. 2, BWV 773, l.h. (which see), 
the trill begins with a definite upward stroke, leading BG to 
misinterpret it as a compound turn-trill. Here, the downward leap 
to the A#4 does suggest the possibility of an compound 
appogiatura-trill, the "Accent-und-Trillo" of the "Explication".

GRACE NOTE, m. 46: P 610 represents this as the "Accent fallend" 
of the "Explication", a small hook at the left of and slightly 
above the A4. Scholarly consensus is that there is no difference at 
all in Bach between this ornament, together with its rising 
companion, the "Accent steigend" (both of which Bach uses 
exclusively in keyboard music), and the grace note represented by 
a small eighth note, which in fact Bach does write in the almost 
identical context of m. 4.