Depending on value mapping to specific file

Hi, well my Scneario is IDoc to File and i have no clue how to achive this:

we get an IDoc with different fields and one of this is field "No" which can have the value 1,2,3

Depending on these values the message should be split and collect all the data-fields wherein the No = 1 or 2 or 3.

After this, the so divided messages should be written in different files.

Can someone tell me how to achive this?!

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Source looks like:

<ZBC0 SEGMENT="1">

<No>1</No>

<TYPE>1B20-6</TYPE>

<SPEC>152J</SPEC>

</ZBC21>

- <ZBC0 SEGMENT="1">

<No>2</No>

<TYPE>1B20-6</TYPE>

<SPEC>152J</SPEC>

</ZBC21>