alexban, the subject here is departure or arrivals PRNAV not the RNAV APPROACH which is similar yet requires some additional considerations. To clear most of doubts here is the link
http://www.ecacnav.com/downloads/PRNAV.mpg
a reference to manual entry is made as well. Basically before any operator uses PRNAV procedures it must obtain approval from the relevant authority. Crews must be trained and documents updated in terms of SOPs, contingency procedures etc.
