MSP430 Pin Variables
the . means a particular bit of a multi-bit output. P4 is not really one pin but a bank of pins! :)


    P4DIR |= BIT6;  /* set P4.6 to output */
    P4OUT |= BIT6;  /* set P4.6 to 1 */
    P4OUT &= ~BIT6; /* set P4.6 to 0 */