Field help (RSDDPMTGR) 

This field is used for a non residual method to specify the equivalent residual method.
This will be automatically substituted for the original method, in plans for the IAS/IFRS or CRC2002-10 standards, during any change influencing the depreciation of an asset : change of method, depreciation, re-evaluation by market value.
The introduction of the residual method is used to process these changes in a long term fashion, by depreciating the new net value for the asset over the duration of the residual depreciation.