Hi Larry,
MBC-97 is very explicit in the second sentence of 22.12.4 (p. 177): "If a vowel sound is to be carried from the last note of one music line to the first note of the next corresponding line, a slur is written after the last note and before the first of their respective lines." It goes on to reinforce this by stating, "The tie is treated in the same manner." (We are all comfortable with brailling the tie at the end and a reminder at the beginning of the next line.)
This says to me that a single slur must always appear at the end of the line when the syllable is continued in the next. Regardless of how many notes are in the first line, that line must end with a slur and the new line must begin with a "reminder" slur; this combination clearly indicates that the syllable continues through the line break.
Proofreading some Bach cantata choral scores, repeatedly I have had to go back to De Garmo to read the slur rules. Finally, at about the 30th time, I realized why I was having so much trouble reconciling the difference between 3 notes at the end of the line and 4+ notes at the end of the line as described in the DG text and illustrated in Examples 31-2 and 31-3. I'm forced to conclude that, according to the Code (and logic), the second sentence of the last paragraph on p. 428 of De Garmo, the bold "except the last" at the top of p. 428, and Example 31-2 do not agree with the Code.
I would appreciate it if you would review these texts too, and tell us if you reach the same conclusion. If the DG material is correct, can you please explain the inconsistency in the use of the final slur?
Dan