i need to create a BAT file which does that following.

-Take a Text file and replace data in it.
(B_)(E_) = (BEGIN) (END)
EX.
F1 VA 5183 19.55150 81.345 89.24340"B_EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"E_EP"
**THIS IS THE ORIGINAL FILE FORMAT IN A *.TXT**

I NEED IT TO LOOK LIKE THIS:
BEG_EP
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
END

AND THE FOLLOWING: "C3_"

F1 VA 5183 19.55150 81.345 89.24340"B_EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"C3_EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"E_EP"

TO LOOK LIKE THIS
BEGIN
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
C3
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
F1 VA 5183 19.55150 81.345 89.24340"EP"
END

Is this possible?
I want to drop the ascii file into the bat file and then it spits it out with all the changes into another file or the same one.... But there is nothing really with fields... just takeing a B_ or E_ and renaming it to a BEG or END on a new line above or below of where that "B_" is located...

I hope this is not hard...

thanks for the help! really!