Generate multiple idocs based on field value

Hi Friends,

I have a mapping requirement.I want to generate multiple idocs if a source segment X appear multiple times in the message and if X segment having field WERKS value start with P.

If X segment appear multiple times in source and field WERKS doesn't start with P, then dont create multiple idocs at target side.

I want to check WERKS value as P only for the first X segment,as if 1st segment contain WERKS value as P all other X segments in the message have same value by default.

Please help me with the complete mapping flow.

Thanks !!

Suresh.