Kenneth, I've never heard of the expression.
The single greatest technical aspect for all cantillation among all the processes for me:
Insure the trachea is completely open, relaxed (not a milimeter of constriction or tension) during inhalation, exhalation and vocalization. So much so that I tell my singers not to even consider the act of inhalation or exhalation in a literal sense, as the open trachea creates a vacuum and passage in/out that enables the diaphragm and lungs to do what comes naturally. An athelete's (swimmer's) catch breath that "sucks" or purposely intakes will insure constriction and less volume filling the lower lung. And,of course, as air will naturally fill the open vacuum of a relaxed trachea, "catch breaths" are virtually silent if done correctly.
It's the closest thing I've experienced to what I've heard called "circular breathing."

I do not know the golden rule you mention, and would be interested to hear it.

Some randomly ordered, experience-based thoughts, and feel free ask me to explain more if needed, though I may not be able to respond quickly~

1- "Round breathing" Take your voice out on 1-2 notes in a long phrase rather than try to jam a panicky breath between notes.
If the schola is small, you will want to choose notes and let your neighbors know so 3 out of 4 singers aren't breathing at once.

2- Breathe sooner than later. Waiting until one is out of air to get a catch breath- or any breath- almost ensures a drop in pitch and disturbance of the legato line. In a mid-size long phrase, taking oneself out for 1-2 notes (usually one note is enough) choose around the halfway point. In a very long phrase, a singer can choose to breathe on notes roughly 1/3 and 2/3 the way through the line.

3- Some scholas give preference in breathing spots to older singers when there are fewer good choices to breathe. I put myself in this older category, as a "moderately severe" asthmatic.

4- The concept of "high-low" breathing reminds singers to aim for a tall and forward resonance while staying strong and grounded in their body. Good resonance and proper support is key to tuning and projection.
With prayerful focus and appropriate energy, the singer gradually makes a habit and allows this open setup to happen. Forcing anything leads to tension in the singing, so forcing in general is to be avoided.

5- During inhalation, the singers should "let the air in" without tension or sound. Allow enough air for the length of the phrase, or for the portion of a long phrase which is sung before a breath. Allowing the appropriate amout of air is very important in chant, as phrase lengths vary considerably. When too much air is taken in, the singer may not have time to get rid of excess air before taking in air for the next phrase. It's not about how much air you have, but how efficiently the air is utilized.

I responded while you were and didn't have the info in your second post.
Since it is just the two of you, I would scrap most general rules that apply to larger groups of singers. Do not feel badly about breathing at quarter bars- even during melismas- if you can do it in such a way that stays steady and smooth. If you stagger in such a way that one of you takes a breath on a note while the other one sings, I suggest that you plan it all out, and write those places on your music. Change as needed, as long as you're coordinating with the other singer. That way the singer who is not breathing is not thrown off, and can better carry the line for the other singer. Then the other guy takes a turn, etc.
You may find that earlier breathing options are better considering the nerves that arise between any rehearsal and Mass. Nervousness often reduces breath control in all singers- even the top pros. That's where the phenomena of "Hey! I know I had enough air to do this in rehearsal so why am I running out of air during Mass (or any performance)!" comes from.

In the scholas at my parish, I have asked singers to circle the notes they use to breathe so they can plan around them and so other singers next to them are more aware of when their neighbor is breathing. In critical places we all choose a spot out loud but we don't always have the need or the time for that. This practice has worked for smaller groups of 2-3 singers for us, too, so hopefully it can help you guys.

You guys can discuss this all day! I shamelessly steal ideas from everyone for future use, and I am getting some good ones here. ;-)

I have a few of those singers, MaryAnn, but they are there for life.

Good and useful info on breathing, btw.

We let the singers think that to humor them. Letting them be the center of attention always gets a high degree of cooperation from those large egos. LOL.

The Golden Rule is referred to in the introduction to the Liber usualis.

Rules for Interpretation.
IX. — The reading and pronunciation of liturgical latin. [sic]
(last page before table of movable feasts)

In the pronunciation and singing of a word the "Golden Rule" must always be kept:
"Never take a breath just before a fresh syllable of a word".

Is this what you were trying to find?

Yes, it means any new syllable. The Liber gives an example and then adds: "A person who is unable to sing this phrase from the quarter-bar to the end in one breath, must be careful not to breathe just before a fresh syllable. The lesser evil would be to breath [sic] after the long note and off its value." I interpret this Golden Rule to mean not only that the schola as a whole shouldn't breathe before a new syllable (except, of course, at a bar line), but that no individual in the schola should breathe there either. This way, the consonants stay in their right place and there are no clipped notes.

Yes, in emergencies, breath between vowels with no consonant (or noticeable glottal for that matter). Easier to find places in Latin than English.

I can see a problem if one tries to breathe between notes and then is late for the next note.
However, if you take your voice out to breathe on a note (see #1 of my first comment, above) you can enter again on a fresh syllable without disruption to the text, provided other singers keep singing and all consonants are coordinated.

Breathing on notes others are singing is a matter of practicality. Far from destroying the integrity of a word, staggered or round breathing in this way preserves the textual phrase when done within an ensemble.
This is something both Dom Saulnier and Wilko Browers recommend, iirc.

because Angels don't need to breathe.

LOL! I always thought this section of Van Eyck's Altarpiece of Ghent was proof that even angels sometimes struggle with chant. Check out some of the expressions:

This is an interesting article regarding vocal technique in the Renaissance.
http://www.maurouberti.it/earlymusic/earlymusic.html
Also Wikipedia
http://en.wikipedia.org/wiki/Renaissance_music

I bring these up because most of us realize that getting two or three chant experts gathered in Turkington's name won't necessarily make his wisdom present. For example, the expressed vocal articulation of a single vowel under a tristopha can be directed in a few differing ways short of ululation! ;-) So, as has been pointed out, once El Jeffe of the duo or schola speaks, ala Ostrowski, do it his or her way is a general good thing.
I know as well that this isn't also germane, but isn't it interesting how, in the classic Renaissance practice exemplfied by Bryd's AVC and Palestrina's Sicut, that notated vowel repetitions are, in fact, almost glottally re-iterated as a performance practice. And by the time you get to the early Baroque with Cassini and others such affectations become standard operating procedures. It's a weird, wonderful world....

LOL!!

Salieri.....perhaps you should invest in guard rails for your bench!!!!

See, go away for a week...

Yes, madorganist, and why I couldn't find it, I don't know. I took a break from the L. Usualis while I learned St. Gall/Laon, so should get back to it in 12 or 15 years.

No, seriously, a point that one expert made about the Rules for Interpretation from the L. Usualis is that they were written BEFORE Mocquereau began seriously exploring chant rhythm. Therefore, this expert said, the Rules are actually more consonant with St. Gall. I realize that getting into the differences between understanding of rhythm is walking into an airplane propeller--not that there are ever any flames on THIS list--so in my mind I have it that the Rules were probably based on practice and less on theory.

For those of you who are wondering what I am talking about, there are two ways to interpret chant: one, which I have seen called "equalism," places essentially the same rhythmic value on each note, with a dot being some form of "doubling," though the use of the word "double" in French and Latin seems to mean more "lengthening" and not strictly multiplying by two.

St. Gall and Laon are the names of monasteries where, many long centuries ago, they developed methods for writing down the way the chants were sung. They are universally referred to by musicians that I have encountered as "the chicken scratches," though as I have finally gotten diligent and learned them, I was recently able to look at the MSS from St. Gall of a simple chant and understand it completely.

The St. Gall marks are clearly conductor's notes--indeed, Dom Cardine keeps reiterating that point in his great book on the semiology of chant--and the editors of the Graduale Novum, the new edition of the Graduale Romanum, have adapted St. Gall in a simpler form to guide interpretation. The movement is much more fluid and varied. http://www.gregor-und-taube.de/html/materialien.htm (The index is annoyingly in German and not Latin, but it is a really wonderful page of resources.)

The young schola director I referred to at the beginning had a hard time understanding why he shouldn't be doing an upbeat as in classic metronome-like conducting, and I had to explain the idea is to conduct speech, as Prof. Mahrt put it so well. (The director is a graduate student at Peabody and quite an accomplished composer. He was fishing around for a new Gloria and being indecisive. I finally said, "Oh, just write one. That's what they did in the 16th Century.")

In one chant we did recently, the St. Gall was quite clear: the first few syllables went quickly up to a high point, which was held--the top of the "Roman Arch" in the phrase--and then the phrase moved away from the high point, but at a slower pace. Prof. Mahrt again describes that well. Very interesting.

Kenneth

Except Adam Wood's. That was not useful. (-: However, I learned breathing by tackling melismas that ran through three or four quarter marks. I called them "breath defying," and clearly the better monasteries had choirs accomplished at staggering their breathing.

The more I am around chant, the more I believe there are not any rules - just points of contention.

I will say, in re: CharlesW's comment, I expected a slightly (very) different atmosphere around chant than in most musical circles (e.g., our musical theater and opera majors here), but I finally concluded, "Everywhere you go, you expect something different, but you always just get human beings."

Kenneth