omitted during Lent, is replaced in pre-1970 forms by the phrase Laus tibi, Domine, rex aeternae gloriae (Praise to thee, O Lord, king of eternal glory) in Lent and the Septuagesima period. The term Alleluia is used also to designate a chant beginning and ending with this word and including a verse of scripture, in particular a chant to greet and welcome the Lord whose word will be proclaimed in the Gospel reading. The choir or a cantor sings "Alleluia". The congregation repeats this. The choir or cantor then sings a verse taken from the Mass Lectionary or the Roman Gradual, after which the congregation again sings "Alleluia". In Lent the verse alone is sung or the word Alleluia is replaced by a different acclamation taken from the Gradual, or a tract is sung. If singing is not used, the Alleluia and its verse may be omitted at any season.<ref name=McNamara>[https://zenit.org/articles/liturgy-q-a-the-alleluia-before-the-gospel/ Edward McNamara, "LITURGY Q & A: The Alleluia Before the Gospel in ZENIT, 6 June 2017]</ref> The complex plainchant setting in the Roman Gradual requires a high degree of skill and is mostly used only in monasteries and seminaries. This melismatic Gregorian chant opens with the cantor singing "Alleluia". The choir repeats it, adding to the final syllable a long melisma called a jubilus. (The Liber Usualis notates the repeat with the Roman numeral "ij" (2) and continues with the jubilus.) The cantor then sings the main part of the verse, and the choir joins in on the final line. The cantor then repeats the opening Alleluia, and the choir repeats only the jubilus. The music is generally ornate, but often within a narrow range. The Alleluia for Christmas Eve, for instance, has an ambitus of only a perfect fifth, a rather extreme example. Alleluias were frequently troped, both with added music and text. It is believed that some early Sequences derived from syllabic text being added to the jubilus, and may be named after the opening words of the Alleluia verse. Alleluias were also among the more frequently used chants to create early organa, such as in the Winchester Troper. The Alleluia and its verse is replaced during Lent and in the pre-1970 form of the Roman Rite Mass also during Septuagesima time by a Tract. On the other hand, during Eastertide the Gradual is replaced with an Alleluia chant, thus putting two such chants before the Gospel