‘Bagging’ is an informal term which means ‘collecting’.
Hill and mountain bagging is very popular in Great Britain, and there are numerous list for different countries and counties.
The great thing about lists is that they offer an incentive to get out there and visit places you might not normally think to go.
To have bagged a Ribu, you must have reached the highest point. For example, lots of people visit the crater rim of Gunung Agung in Bali, but far less people actually reach the highest point itself.
You may find the following two files useful in planning your hiking trips across the Indonesian archipelago:
An Excel spreadsheet with all the Ribus and Spesials listed, along with elevation, prominence, province, plus latitutde and longitude data.
A KML file with all the Ribus and Spesials listed, for use with Google Earth.