Hello,

Yes 7 year preceding study certificate means 1 to 12 class study certificate.

Like 10th and 12th marksheet and certificate and class 1st to 4th one certificate and 5th to 7th one certificate and 8th to 10th one certificate.

Actually its a confirmation that you are leaving which state.

And you must be signed every certificate by BEO or DDPI.

All the best.