How to use OR in an If Statement

Morning All

I need to use an or in my if statement within the design of the bip template.

I need to base the code on my tag TRX_TYPE. So my template must look at the tag and if it does not equal two particular TRX_TYPE's then it must produce certain results.

How can I use an or in my if statement?

I have two if's that displays different output:

1. <?if:TRX_TYPE='CDC CCT Invoice'?>
2. <?if:TRX_TYPE='CDC Property Invoice'?>

Now the last code needs to display no results if the TRX_TYPE is not one of these two.