This is a sequence of letters which describes how automatic formatting is to be done. See |fo-table|. When the 'paste' option is on, no formatting is done (like 'formatoptions' is empty). Commas can be inserted for readability. To avoid problems with flags that are added in the future, use the "+=" and "-=" feature of ":set" |add-option-flags|. NOTE: This option is set to the Vi default value when 'compatible' is set and to the Vim default value when 'compatible' is reset.