Moving Null to a Character variable

I have a Data Structure declared as below.

DbTLogonMsg       DS
D bMsgCode                    5A
D bMsgLen                        5A  INZ(' ')

C MOVE     *BLANKS     bMsgCode

I initialized one subfield with Blanks and Moved Blanks to another
subfield.

In RPG, Moving Blanks and Moving NULL to a Character variable are same or
different?
If it is different, how to move NULL to a Character Variable?

Thanks in advance for your responses.

Regards
Lakshmi



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