Column heading meanings of spirometry test results

Hello,

I recently received the report for my PFTs and wanted to ask what the column headings mean:

"Ref" is reference?

"Pre meas" is that predicted measurement or does the "pre" stand for before?

"Pre % Ref"

"Post Meas"

"Pos % Ref"

"Post % Chg"

"CI"

I will meet with the pulmonologist, sure, but meantime, I wanted to get a headstart on deciphering my results. Thank you!