Thank you guys for the advises,
I just have tried this way:
INITIALIZATION.
s_fkdat-SIGN = 'I'.
s_fkdat-OPTION = 'BT'.
s_fkdat-HIGH = sy-datum - 7.
s_fkdat-LOW = sy-datum - 2.
APPEND s_fkdat.
Small question: how to declare such a variables like s_fkdat_SIGN in the best way?
