Q: What are the limitations on Mass prayers and readings when the wedding Mass is on Pentecost afternoon, not at a parish Mass?
A: A Mass on Pentecost afternoon must be the Pentecost Mass. A wedding may take place during the Mass, but the presidential prayers and readings—even the vesture—are those of Pentecost.
See Order of Celebrating Matrimony 34. The final paragraph, I believe, relates only to the previous paragraph, not to the first. So it does not give permission for substituting a reading at a Pentecost Mass.
The rule repeats at OCM 54.
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