I should have printed an example, but will try to remember. Lately when I pull up metars in USA using acars I am seeing something I’m not familiar and can’t find in books available to me
metar main body, comments and then breakdown on temps T025.1010, a SLP and then a 5 digit number like (51001)
it is this 5 digit number I’m having trouble with

A five digit block commencing with 5 is the pressure trend over the previous 3 hours. The second digit (1) indicates the pressure was increasing, then steady, or increasing slowly. The last three digits are the pressure change in tenths of hPa.
See: METAR & TAF Decoding

Thanks for the info