Partial reload script why need to "load [Reporting Code]," ?

[paulyeo11]

Hi All

I have below code using for partial reload :-

TABLE_P:

left keep (GL_TABLE)

load [Reporting Code],

if([AccountCode]>=5000000 and [AccountCode]<=5999999,'P_Revenue') as [P_Revenue_]

resident GL_TABLE;

I cannot understand why need to "load [Reporting Code]," ?

Hope some one can share with me.

Paul