delete-trailing-linesdelete-trailing-lines is a variable defined in `
simple.el'. Its value is
tDocumentation: If non-nil, M-x delete-trailing-whitespace deletes trailing lines. Trailing lines are deleted only if `delete-trailing-whitespace' is called on the entire buffer (rather than an active region). You can customize this variable. This variable was introduced, or its default value was changed, in version 24.3 of Emacs.