how to refer a text window from coding in the smartform

<b>how to refer a text window from coding in the smartform </b>

there are two text window. in one window "service request form" is written and in other "purchase request form" is written it should written "service" when service is required else it should written "purchase"

i am taking the length of the service number [ to print service or purchase ] but i dont know how to refer the text window

or is any other logic is there to do that