Twip is the unit for measurement that will be used in Rpv.
If you are familiar with visual languages then you may know this, but if you are not, it is very simple.
Each centimeter is 567 twips and each inch is 1440 twips.
We can say then that {1440} means that the text will be print one inch after the left margin.
The spacing setting is 200 twips by default, which means that it is less than about 0.30 centimeter.
The values expressed in twips are going to be used to draw boxes, lines, specify the spacing, declare the position of columns, etc.