四分律比丘含注戒本 2.49

2.49

謂誦句義、句味、字義也。非句義亦爾。言「句義」者，同誦不前不後也。非句義者，如一人說「諸惡莫作」未竟，第一人抄同。句味者，「眼無常」等。非句味者，抄前也。字義者，同誦「阿」字也。非字義者，抄前「阿」字也。

This means reciting phrases and their meaning, phrases and their phrasing, or syllables and their meaning. Non-phrases and meaning are also like this. "Phrases and meaning" means reciting together neither ahead nor behind. "Non-phrases and meaning" means, for example, when one person has not finished uttering "Refrain from all evil," the second person overlaps and joins in. "Phrases and phrasing" means [reciting] "The eye is impermanent," and so on. "Non-phrases and phrasing" means overlapping what precedes. "Syllables and meaning" means reciting the syllable "a" together. "Non-syllables and meaning" means overlapping the preceding syllable "a".