— Command: insert-buffer from-buffer-or-name

This command inserts the entire contents of from-buffer-or-name (which must exist) into the current buffer after point. It leaves the mark after the inserted text. The value is nil.

— Command: self-insert-command count

This command inserts the last character typed; it does so count times, before point, and returns nil. Most printing characters are bound to this command. In routine use, self-insert-command is the most frequently called function in Emacs, but programs rarely use it except to install it on a keymap.

In an interactive call, count is the numeric prefix argument.

This command calls auto-fill-function whenever that is non-nil and the character inserted is in the table auto-fill-chars (see Auto Filling).

This command performs abbrev expansion if Abbrev mode is enabled and the inserted character does not have word-constituent syntax. (See Abbrevs, and Syntax Class Table.)

This is also responsible for calling blink-paren-function when the inserted character has close parenthesis syntax (see Blinking).

Do not try substituting your own definition of self-insert-command for the standard one. The editor command loop handles this function specially.

— Command: newline &optional number-of-newlines

This command inserts newlines into the current buffer before point. If number-of-newlines is supplied, that many newline characters are inserted.

This function calls auto-fill-function if the current column number is greater than the value of fill-column and number-of-newlines is nil. Typically what auto-fill-function does is insert a newline; thus, the overall result in this case is to insert two newlines at different places: one at point, and another earlier in the line. newline does not auto-fill if number-of-newlines is non-nil.

This command indents to the left margin if that is not zero. See Margins.

The value returned is nil. In an interactive call, count is the numeric prefix argument.

— Command: split-line

This command splits the current line, moving the portion of the line after point down vertically so that it is on the next line directly below where it was before. Whitespace is inserted as needed at the beginning of the lower line, using the indent-to function. split-line returns the position of point.

Programs hardly ever use this function.

— Variable: overwrite-mode

This variable controls whether overwrite mode is in effect. The value should be overwrite-mode-textual, overwrite-mode-binary, or nil. overwrite-mode-textual specifies textual overwrite mode (treats newlines and tabs specially), and overwrite-mode-binary specifies binary overwrite mode (treats newlines and tabs like any other characters).