Boeing 737-200 callouts during short final

[lynnpype]

Hello,

I recently saw a video covering ILS approaches in a Boeing 737-200. I have a question regarding particular callouts made before landing.

During every approach, the PNF called out a series of numbers with approximately 5 seconds between each callout, like this:

"plus 867 (5 seconds)
plus 767 (5 seconds (also at every callout below))
plus 868
plus 1067
plus 867"

or

"plus 567
plus 567
plus 867
plus 867
plus 767
plus 767
plus 567"

These callouts were made during short final, after finishing the landing checklist until touchdown (during one occasion a callout was even made 2 seconds before touchdown).

I didn't hear these kind of callouts during similar approaches in Boeing 737-400's or -800's.

What are they exactly calling out?

Thank you, kind regards,
Lynn Pype