Part III-5. Exposition of the Blessed Sacrament
60. Exposition of the blessed sacrament, either in a ciborium or a monstrance, draws the faithful to an awareness of the sublime presence of Christ and invites them to inner communion with him. Therefore, it is a strong encouragement toward the worship owed to Christ in spirit and in truth.
In such exposition care must be taken that the signs of it bring out the meaning of eucharistic worship in its correlation with the Mass. This end is served in the case of solemn and prolonged exposition by having it take place at the end of the Mass in which the host to be exposed for adoration has been consecrated. The Mass itself ends with the Benedicamus Domino, without the blessing. In the surroundings of exposition,  anything must be carefully avoided that could in any way obscure Christ's intention of instituting the holy eucharist above all in order to be near us to feed, to heal, and to comfort us. 
Prohibition of Mass Before the Exposed Blessed Sacrament
61. The celebration of Mass is prohibited within the body of the church during exposition of the blessed sacrament, all contrary concessions and traditions hitherto in force, even those worthy of special mention, not withstanding.
For, in addition to the reasons given in no. 55 of this Instruction, the celebration of the eucharistic mystery includes in a higher way the inner communion to which exposition is meant to lead the faithful and does not need the support of exposition.
If exposition of the blessed sacrament goes on for a day or for several successive days, it should be interrupted during the celebration of Mass, unless it is celebrated in a chapel separate from the area of exposition and at least some of the faithful remain in adoration.
In those places where a break with long-established, contrary custom would upset the faithful, the local Ordinary should fix a sufficient but not overly long period for instructing them before the present norm takes effect.
Arrangement of the Rite of Exposition
62. For brief exposition, the ciborium or monstrance should be placed on the altar table; for a longer exposition a throne can be used and set in a prominent, but not too elevated or distant position.
During the exposition everything should be so arranged that the faithful can devote themselves attentively in prayer to Christ the Lord.
To foster intimate prayer, readings from sacred Scripture, together with a homily or brief inspirational words lead to a better understanding of the eucharistic mystery, are permitted. It is proper for the people to respond to the word of God with singing. There should also be suitable intervals of silence. At the end of the exposition, benediction is given.
When the vernacular is used, another eucharistic hymn, at the discretion of the conference of bishops, may be substituted for the Tantum ergo as the hymn to be sung before the benediction.
Annual Solemn Exposition
63. In churches where the eucharist is regularly reserved, there may be an annual, solemn exposition of the blessed sacrament for an extended period of time, even if not strictly continuous, so that the local community may meditate on this mystery more deeply and adore.
Exposition of this kind may take place only if the participation of a reasonable number of the faithful is ensured, the local Ordinary consents, and the established norms are followed.
64. For any serious and general need, the local Ordinary may order prayer before the blessed sacrament exposed over a longer period (which may be strictly continuous) in those churches to which the faithful come in large numbers.
Interruption of Exposition
65. Where there cannot be uninterrupted exposition, because there is not a sufficient number of worshipers, it is permissible to replace the blessed sacrament in the tabernacle at fixed hours that are announced ahead of time. But this may not be done more than twice a day, for example, at midday and at night.
This reposition can be simple without singing: the priest vested in surplice and stole, after a brief adoration of the blessed sacrament, places it in the tabernacle. At a set time, the exposition is resumed in a similar way, following which the priest, after a brief period of adoration, leaves.
Exposition for Short Periods
66. Even short exposition of the blessed sacrament, conducted in accord with the norms of the law, must be so arranged that before the benediction reasonable time is provided for readings of the word of God, hymns, prayers, and silent prayer, as circumstances permit.
Local Ordinaries will make certain that these expositions of the blessed sacrament are always and everywhere marked with proper reverence.
Exposition merely for the purpose of giving benediction after Mass is prohibited.