The meaning of prefix 'first'

[jinniulema]

Hello, I find there are many variables which have a prefix 'first'. For example, 'first_label'. Can you explain the meaning of 'first' here?

[Akeepers]

• 'first' - trigger
• 'second' - argument

The 'first' is a code snippet related to the event extraction task. Please ignore if it's not relevant to your question.

[jinniulema]

Ok, thanks