Procedure from library latex.lib (see section latex_lib).
latex.lib
opentex(fname); fname string
nothing; writes a LaTeX2e header into a new file <fname>.
<fname>
preceding ">>" are deleted and suffix ".tex" (if not given) is added to fname.
fname
Example:
LIB "latex.lib"; opentex("exmpl"); texobj("exmpl","hello"); closetex("exmpl");