Code of Rubrics (Codex Rubricarum), we wished to avoid discussions, since it is indeed a post for reference, i.e., it is intended for those simply looking for online sources on the rubrics and general liturgical rules of the "Extraordinary Form" of the Roman Rite.
This begins a series of open threads on the liturgical rules of the Traditional Latin Mass. Remember that these are the rules in force - so, please, discuss at will, but avoid angry generalizations such as, "Bugnini lied, people died."
The Codex Rubricarum (1960) of the "1962 Roman Missal" states the following regarding the "active participation of the faithful":
"272. The Mass of its very nature requires that all present should participate in it, in the manner proper to each one.
"The various ways in which the faithful can actively participate in the holy Sacrifice of the Mass should be so arranged that all danger of abuse is removed, and that the principal end of their participation is secured, namely a more complete worship of God and edification of the faithful.
"The active participation of the faithhful was dealt with in greater detail in the Instruction on Sacred Music and Liturgy, promulgated on 3rd September, 1958."
The referred document, the Instruction De musica sacra et sacra liturgia, approved by Pope Pius XII at the very end of his pontificate, includes these points on the participation of the faithful in Low Mass. Notice that, except for the abolition of the playing of musical instruments during certain silent parts of the Mass and the recommendation to the Priest of n. 34, the other rules are optional, even if some could possibly be understood as recommended.
c. Participation of the faithful in low Mass. [De fidelium participatione in Missis lectis]
28. Care must be taken that the faithful assist at low Mass, too, "not as strangers or mute spectators" (Divini cultus, Dec. 20, 1928: AAS 21  40), but as exercising that kind of participation demanded by so great, and fruitful a mystery.
29. The first way the faithful can participate in the low Mass is for each one, on his own initiative, to pay devout attention to the more important parts of the Mass (interior participation), or by following the approved customs in various localities (exterior participation).
Those who use a small missal, suitable to their own understanding, and pray with priest in the very words of the Church, are worthy of special praise. But all are not equally capable of correctly understanding the rites, and liturgical formulas; nor does everyone possess the same spiritual needs; nor do these needs remain constant in the same individual. Therefore, these people may find a more suitable or easier method of participation in the Mass when "they meditate devoutly on the mysteries of Jesus Christ, or perform other devotional exercises, and offer prayers which, though different in form from those of the sacred rites, are in essential harmony with them" (Mediator Dei, AAS 39  560-561).
In this regard, it must be noted that if any local custom of playing the organ during low Mass might interfere with the participation of the faithful, either by common prayer or song, the custom is to be abolished. This applies not only to the organ, but also to the harmonium or any other musical instrument which is played without interruption. Therefore, in such Masses, there should be no instrumental music at the following times:
a. After the priest reaches the altar until the Offertory;b. From the first versicles before the Preface until the Sanctus inclusive;c. From the Consecration until the Pater Noster, where the custom obtains;d. From the Pater Noster to the Agnus Dei inclusive; at the Confiteor before the Communion of the faithful; while the Postcommunion prayer is being said, and during the Blessing at the end of the Mass.
Prayers and Hymns
30. The faithful can participate another way at the Eucharistic Sacrifice by saying prayers together or by singing hymns. The prayers and hymns must be chosen appropriately for the respective parts of the Mass, and as indicated in paragraph 14c.
31. A final method of participation, and the most perfect form, is for the congregation to make the liturgical responses to the prayers of the priest, thus holding a sort of dialogue with him, and reciting aloud the parts which properly belong to them.
There are four degrees or stages of this participation:
a) First, the congregation may make the easier liturgical responses to the prayers of the priest: Amen; Et cum spiritu tuo; Deo gratias; Gloria tibi Domine; Laus tibi, Christe; Habemus ad Dominum; Dignum et justum est; Sed libera nos a malo;b) Secondly, the congregation may also say prayers, which, according to the rubrics, are said by the server, including the Confiteor, and the triple Domine non sum dignus before the faithful receive Holy Communion;c) Thirdly, the congregation may say aloud with the celebrant parts of the Ordinary of the Mass: Gloria in excelsis Deo; Credo; Sanctus-Benedictus; Agnus Dei;d) Fourthly, the congregation may also recite with the priest parts of the Proper of the Mass: Introit, Gradual, Offertory, Communion. Only more advanced groups who have been well trained will be able to participate with becoming dignity in this manner.
32. Since the Pater Noster is a fitting, and ancient prayer of preparation for Communion, the entire congregation may recite this prayer in unison with the priest in low Masses; the Amen at the end is to be said by all. This is to be done only in Latin, never in the vernacular.
33. The faithful may sing hymns during low Mass, if they are appropriate to the various parts of the mass.
34. Where the rubrics prescribe the clara voce, the celebrant must recite the prayers loud enough so that the faithful can properly, and conveniently follow the sacred rites. This must be given special attention in a large church, and before a large congregation.
Please, discuss freely, but respectfully: avoid making irreversible and resolute comments about situations you have never experienced (for instance, it is likely that, if you live in an English-speaking nation, you may have never been to a "Dialogue Mass", and even then consider it "dangerous" to the faith; while, if you live in any other area, the "Dialogue Mass" could be the only kind of Low Mass you know, and the Low Mass in the presence of a congregation, but responded by the server only, might seem unimaginable). Are they practical? Are they followed in your regular Mass? Should they be avoided - partly or completely? Any other opinions?