The translation for "index" is Register in Danish and Norwegian.
The printed record format introduced in Denmark and Norway in the 1812 to 1814 time period had place in the back of the church book for what was supposed to be a comprehensive index. Across the double page were columns for listing the name, and then the page numbers of a person's birth or christening, confirmation, marriage, death, move in, move out, and vaccination. If a person was born, married, or died in the parish, this register could have been a marvelous tool.
Unfortunately, most ministers just recorded the events chronologically under the first name, a shortened version of what was in the actual record. Sometimes, they would letter-group everyone by first name, i.e. all the Anders, Annes, Andreases, Ambrosius' and so forth were together, in rough chronological order under the As, then the Bs would come, and so forth.
It has been found, however, that sometimes an entry will be in the register which will not appear in the actual church book. If you're having a tough problem, be sure to check all records, including the register.