5.21.1.4.1. Destination and information numbers: The general modification
method 
The numerous numbers in a network can basically be divided into two
categories:
- The numbers which describe the destination (e.g. the B subscriber of the "called number")
- The numbers provided as additional information (e.g. information on the A subscriber of the "calling number" or the forwarding subscriber in the "redirecting number" o. "last rerouting number")
Numbers of the first category are handled by WABE and LCR and modified
accordingly. Here, they should generally be called "destination numbers."
By contrast, numbers of the second category are modified using AMO KNMAT,
AMO KNPRE, AMO KNFOR, and AMO KNDEF. The "information numbers" modified
in this manner are called "calling numbers" in this document. The modification
method itself is designated by the term "INS" (Info Number Signaling).
For many features, the number previously specified as additional information
is used as the destination number in a later procedure (e.g. stored number
redial, callback, etc.). For this reason, it is the objective of the
INS to treat the number in such a way the point it is addressing can
be called at any time and place in the network.
RULE:
The information numbers must always be modified in such away that
the point they are addressing can be reached from any transmitting location
in the network and at any time!