''Supremi disciplinae'' was a ''

motu proprio In law, ''motu proprio'' (Latin for "on his own impulse") describes an official act taken without a formal request from another party. Some jurisdictions use the term ''sua sponte'' for the same concept. In Catholic canon law, it refers to a do ...

'' released on 2 July 1911 by

Pope Pius X Pope Pius X ( it, Pio X; born Giuseppe Melchiorre Sarto; 2 June 1835 – 20 August 1914) was head of the Catholic Church from 4 August 1903 to his death in August 1914. Pius X is known for vigorously opposing modernist interpretations of C ...

that reduced the number of

holy days of obligation In the Catholic Church, holy days of obligation are days on which the faithful are expected to attend Mass, and engage in rest from work and recreation (id est, they are to refrain from engaging in work or activities that hinder the worship owed t ...

within the Roman

Catholic Church The Catholic Church, also known as the Roman Catholic Church, is the largest Christian church, with 1.3 billion baptized Catholics worldwide . It is among the world's oldest and largest international institutions, and has played a ...

. It reduced the number of such non-Sunday holy days from 36 to 8. The present list was established in 1917.''Codex Iuris Canonici'' canon 1247 (1917).

References

Motu proprio {{RC-Canon-law-stub