SAP Note 18861 - Changing factors for currencies from table TCURR

Symptom:

Changing the relations from table TCURR (factors for the currency units) leads to inconsistent system statuses.
Example:
- Order is created with currency relation 1:1.
- Relation is changed 1:100.
- The relation 1:100 is generated for the billing and leads to incorrect invoice amounts.

Cause and prerequisites

The R/3 System is not designed for these kind of changes of the base structure.

Solution
The relations from table TCURR must not be changed for periods of less than a year.
A general solution of this problem exists as of Release 4.0A.