The total width of the format area. The margins, indentation, and text are formatted into this space. The value provided is silently converted to a positive integer.

                           COLUMNS
<-------------------------------------------------------------->
<-----------><------><---------------------------><------------>
 left margin  indent  text is formatted into here  right margin

Source Code

# File action_mailer/vendor/text-format-0.6.3/text/format.rb, line 187
def columns=(c)
  @columns = posint(c)
end