Absolute or Relative pressure to WU

Apologies is this has already been answered but I can't find it anywhere. I just set up a PWS at my house. I am submitting the data to Weather Underground through their PWS upload protocol ( https://support.weather.com/s/article/PWS-Upload-Protocol ). It is not clear weather I should send relative or absolute pressure. ChatGPT tells me to send absolute. Gemini tells me to send relative. The stations closest to me are a mix of both. Is there a best practice or expectation on this?