For all of Paschaltide, with the exception of the Octaves of Pascha, the Ascension and Pentecost, the psalms of each nocturn of Mattins are sung under one antiphon. In the ferial Office this is Alleluia and on feasts the first antiphon of each nocturn.
Likewise the psalms of Lauds, Vespers and the Hours are sung under a single antiphon.
On all ferial days the antiphon on the Benedictus and Magnificat is proper.
The Commemoration of the Cross is sung on semidoubles and lower ranking days outside Octaves. The structure of this commemoration is as follows:
Ant. Crucifixus surrexit a mortuis, et redemit nos, alleluia, alleluia.
V. Dicite in nationibus, alleluia. R. Quia Dominus regnavit a lingo, alleluia.
Deus, qui pro nobis Filium tuum Crucis patibulum subire voluisti, ut inimici a nobis expelleres potestatem: concede nobis, famulis tuis; ut resurrectionis gratiam consequamur. Per eumdem Dominum nostrum.
At Prime the festal Regi saeculorum is sung on all ferial days. In the short responsory the versicle Qui resurrexisti a mortuis, Alleluia, Alleluia is sung.
Apostles and Martyrs have their own Commons for Paschaltide. In other Offices Alleluia is added to the invitatory of Mattins, the antiphon of the nocturns and the versicles and their responses. A double Alleluia is added to the short responsories at the Hours and Compline.
At Mass two Alleluias are added to the Introit and in place of the Gradual after the Epistle a special Paschaltide Alleluia is sung consisting of two Alleluias followed by a verse and Alleluia and then a second verse and Alleluia.
(My, free style, translation of the rubrics in the Ordo, p.33)