In an Alda score, a series of notes or other events can be captured as a sequence by enclosing it in square brackets:

[c d e f c1/e/g]

On its own, this is nothing special; the score is still essentially the same, and sounds the same. However, capturing a sequence of events allows you to do special things like repeat the sequence several times in a row, or store it in a variable and use it later.