tā
The modifier tā refers to the bottom of something. So, rā NP tā is to the bottom of NP or under NP and rū NP tā is from the bottom of NP.
rājatā
rājatā is rā NP tā without a specified location, and so means ‘to the bottom’ or ‘under’.
rūjatā
Likewise rūjatā is rū NP tā without a specified location, and so means ‘from the bottom’ or ‘from under’.