jtag pin function question

hi all

i have a newbie question: what do the Vcc_in and Vcc_out pins on my jtag programmer do? im looking at the schematic for the msp430h1232 and theyre wired to whats effectively an spdt switch . it kinda looks like some kind of power switch my guess would be that the jumper positions determine if the programmer powers the circuit or vice versa. does anyone know if im right or not ide kinda like to know how to hook them up right so i dont let the smoke out of my programmer or my chips

thanks

download the PDF file for Hxxx there is explained

P-IN feeds power from JTAG to target

P-OUT makes JTAG to follow target voltage

Tsvetan