Link

http://www.shusterman.com/hl-99regs.html

In addition, the Service is considering expanding the dual intent
concept to cover other long term nonimmigrants who are visiting this
country as traders (E-1), investors (E-2), students (F-1, J-1 or M-1),
or scholars (J-1), etc. These nonimmigrants, who are typically
authorized to stay in this country for considerable lengths of time,
often need to make short overseas travels during their authorized stay.
Under the ``dual intent'' doctrine, these nonimmigrants would be able
to maintain valid nonimmigrant status and travel overseas without
advance parole while applying for adjustment of status.
The Service has, traditionally, considered applying for adjustment
of status as relevant evidence in determining whether an alien has
abandoned the requisite nonimmigrant intent. Section 214(b) of the Act
does not, however, require the Service to hold this position as an
absolute rule. So long as the alien clearly intends to comply with the
requirements of his or her nonimmigrant status, the fact that the alien
would like to become a permanent resident, if the law permits this,
does not bar the alien's continued holding of a nonimmigrant status.