Recently I have attained a Roman Missal so as to better follow the Traditional Latin Mass. In its introduction it contains different sections on the Catholic Faith and how to live it. One of these sections describes the proper etiquette one should observe while at the Holy Sacrifice of the Mass. I thought it was interesting, so I figured I would translate it (from Spanish) in the hopes that it may be useful for anyone who is looking to understand what reverence should be shown to our Lord while in His presence. Enjoy.

Upon entering the temple where it is reserved with due posture, make a simple genuflection (bending the right knee until it touches the floor) towards the Tabernacle. Above all direct yourself to the altar of the Sacrament, and bending both knees, pray for some time. It is not proper to direct one's prayers to any image without first directing oneself to Jesus Christ, truly present in the Eucharist. It is also irreverent to immediately seat oneself without first praying on one's knees for a few moments; and it is disrespectful to greet and speak with acquaintances.

Whenever you pass in front of the altar of the Sacrament make a simple genuflection; do the same whenever you pass in front of an altar where the Holy Mass is being celebrated. In passing in front of an altar where the Holiest of Holies is solemnly displayed, or where Holy Communion is being distributed, it is proper to make a double genuflection (bending both knees and bowing one's head). While the priest consecrates or elevates the Host or the Chalice, all the faithful should remain kneeling, and not moving from one place to another. The same should be done when a priest moves the Holiest of Holies, until he has passed.

Prayed Mass. The Rubric supposes that the entire Mass, except the Gospels, is heard kneeling. If you cannot remain knelt without significant discomfort, change your posture in the following manner:

Standing. 1) During both Gospels and during the Creed (making a simple genuflection at Et incarnatus est^[a] and at Verbum caro factum est^[b]). 2) During the preface. 3) From the Dominus vobiscum [the Lord be with you] that precedes the Postcommunion, until the ite, Missa est [go in peace].

Seated. 1) From the Offering Prayer until the beginning of the Preface. 2) Once the priest and the faithful have received Communion, until the Dominus vobiscum that precedes the Postcommunion.

Kneeling. Everything else.

Solemn Mass. Kneeling. 1) From the beginning until the end of the first incensing. 2) During the Creed, while the choir sings the Incarnatus est. 3) From the Sanctus until the end of Holy Communion. 4) When receiving the blessing.

Standing. From the Introito until the beginning of the Epistle. 2) During the chanting of the Gospel until the minister finishes praying the Creed, joining the minister in a simple genuflection at Et incarnatus est. 3) During the incensing of the offering. 4) During the Preface. 5) From the Dominus vobiscum that precedes the Postcommunion, until the ite, Missa est. 6) During the final Gospel, making a simple genuflection at et Verbum caro factum est.

Seated. 1) Whenever the minister is seated, except when the et incarnatus est is sung during the Creed, where you will be kneeling. 2) During the chant of the Epistle until the Gospel chant begins. 3) From the Offering Prayer until the beginning of the incensing; and upon its completion, until the Preface. 4) When Communion has ended, until the Dominus vobiscum that precedes the Postcommunion.

[a] This is in reference to the incarnation section of the Nicene Creed, which corresponds in the English version that says "he came down from Heaven, and by the Holy Spirit was incarnate of the Virgin Mary, and became man."

[b] This refers specifically to a section which is read at the end of the Traditional Latin Liturgy which is a reading of John I, specifically verse XIV at "and the Word was made flesh."