tex-region
tex-region is an interactive compiled Lisp function in `tex-mode.el
'.
(tex-region BEG END)
Run TeX on the current region, via a temporary file.
The file's name comes from the variable `tex-zap-file' and the
variable `tex-directory' says where to put it.
If the buffer has a header, the header is given to TeX before the
region itself. The buffer's header is all lines between the strings
defined by `tex-start-of-header' and `tex-end-of-header' inclusive.
The header must start in the first 100 lines of the buffer.
The value of `tex-trailer' is given to TeX as input after the region.
The value of `tex-command' specifies the command to use to run TeX.