Ageing report-Days range as an I/p

Question

Based on posting date we designed an Ageing report
0  30  60  90  120  ....
now users want day range as an i/p
means => user will i/p day range say 40 then report will be executed for 0  40  80  120 .....
if i/p for day range is 60 then 0  60  120  180 ......
previously we resticted the key figure by posting date variable by settng the offset range
like RFK1--- 0balance restricted by var (0-30)
      RKF2--- 0balance restricted by var (31-60) and so on...
before we were able to hardcore it but with the current requirment we have to take user i/p var and then accordingly ageing report will be generated..
pl let us know the right way

Answer 1

okay...
we have created one char : ZOFFSET (no of days) and included in the target on which ageing report is based on...,,,, after that we crearted a user exit variable Zvar_offset(ready for i/p) on char ZOFFSET.....
In ZXRSRU01,
when zpost_dt  {zpost_dt is the user exit variable ,ready for i/p,defined for posting date}
if i_step = 1
date_low = zpost_dt.
date_high = zpost_dt - Zvar_offset. {not sure whether this logic will work or not!!!}
CLEAR L_S_RANGE.
L_S_RANGE-LOW  = date_low.
L_S_RANGE-high  = date_high.
L_S_RANGE-SIGN = 'I'.
L_S_RANGE-OPT  = 'BT'.
APPEND L_S_RANGE TO E_T_RANGE.
even after this we cant achieve the motive, as zpost_dt will have range value high and low after user exit execution  but in our query its a single value i/p (user will give only one posting date) ,,,
also what abt other buckets (other ranges for the same offset) because code will return only one range however we want more ranges for different intervals