The .PAGE SIZE command sets the page "frame" by specifying the
    page length (the maximum number of lines of text on a page)
    and the page width for the running heads. (Compare with .RIGHT
    MARGIN, which sets the text width.) The width component of .PAGE
    SIZE and the value established by .RIGHT MARGIN are separate
    values.

    Format

      .PAGE SIZE  [[+/-]n1] [,[+/-]n2]

    Abreviated format

      .PS  [[+/-]n1] [,[+/-]n2]