Master of Ceremonies wears purple at High Masses according to the Extraordinary Form of the Mass?
I can recall reading in some liturgical book that the Master of Ceremonies (MC) had the privilege of wearing purple (at least the sash) when fulfilling this office at the High Mass in accordance with some norm of rubrics according to the Tridentine Rite. Most MCs would not avail themselves of this privilege. The MC does not have to be a priest, but could be a cleric of lower rank (even a seminarian).
While watching this YouTube video Levithögmässa. 23 november 2019, Göteborg, it is quite apparent that the MC is availing himself of this privilege. It seems equally possible the Master of Ceremonies is a seminarian!
My question is as follows: Can anyone direct me to a reference indicating the use of a Master of Ceremonies wearing either a purple sash and black soutane or a purple sash and purple soutane?
Once again, I know I have read about it, but I can not recall the source! It may in fact only be a local tradition? I also can recall that the purple sash could be worn.