Snorkel weak labeling for NER. When a token does not fall under any of the class labels or abstains in NER?

I have a program that labels a sequence of words using ontologies. I have labeling functions for class negative, class positive, and class abstain. Should I keep the word unlabeled if it does not fall under any of these class labels and ignore it or should I force-label them under either class negative or abstain? I will be grateful for any hints or help.

deeplearning labeling labels