This is copied and pasted from the OU website:
https://oukosher.org/the-kosher-primer/
XIV. Pareve Foods:
A. OU policy is that dairy or meat items are labeled OU-D and OU Dairy or OU Meat respectively. An item that is labeled OU without a suffix can be assumed to be pareve. Nonetheless, we recommend checking the ingredients listed on the label, since on rare occasions, the OU-D is inadvertently omitted.