DEFUN ("write-region", Fwrite_region, Swrite_region, 3, 7,
"r\nFWrite region to file: \ni\ni\ni\np",
doc: /* Write current region into specified file.
-When called from a program, takes three arguments:
-START, END and FILENAME. START and END are buffer positions.
+When called from a program, requires three arguments:
+START, END and FILENAME. START and END are normally buffer positions
+specifying the part of the buffer to write.
+If START is nil, that means to use the entire buffer contents.
+If START is a string, then output that string to the file
+instead of any buffer contents; END is ignored.
+
Optional fourth argument APPEND if non-nil means
append to existing file contents (if any). If it is an integer,
seek to that offset in the file before writing.
If MUSTBENEW is neither nil nor `excl', that means ask for
confirmation before overwriting, but do go ahead and overwrite the file
if the user confirms.
-Kludgy feature: if START is a string, then that string is written
-to the file, instead of any buffer contents, and END is ignored.
This does code conversion according to the value of
`coding-system-for-write', `buffer-file-coding-system', or