What is the author's style in Three To's and an Oi by Heather McHugh?

In most poems, the individual lines are clustered into stanzas, or groups of lines. The most common stanza length is the quatrain, or four-line grouping, although the lengths of stanzas can vary from poem to poem and sometimes even within a poem, producing a free-form style, also called “open form.” “Three To's and an Oi” is a mix of stanzaic formality with open-form structure. The poem is formal in that McHugh uses two-line stanzas consistently, from start to end. Although the number of lines in each stanza stays the same, the lengths of the lines vary widely throughout the poem, and there is no set meter or rhyme scheme. The consistency of the stanzas gives the poem a measured feel, which indicates the author's control. The lack of other formal elements has the opposite effect, reinforcing the poem's idea of underlying dread, as if the poet is not able to stay with any prolonged sequence of thought owing to an awareness of the futility of logic.