Pullup/Pulldown status of a microcontroller's pin

Hi,

What does it mean when the status of a microcontroller's pin is given as I (pullup) or I (pulldown)? Please have a look at page 18 & 19 of this datasheet.
**broken link removed**
Also what needs to be done with these microcontroller pins if they are not used? Can they be simply left soldered?

Thanks

The pull down TST pin is connected to VSS (common).
You can set them as Output if not used.
Max.