PADP (Scotland) decision letter - does it include justification

(I can’t see a flair for Pension Age Disability Payment so used this one.)

Does anyone with experience of Scotland know what format the decision letter for PADP is?

I’ve applied for my dad as a ‘Third Party Applicant’, not an appointee so imagine the decision letter will go to him.

Will it just be a letter? am I correct in thinking no report unless asked for?

or does he get some sort of justification for their decision either way?

even if it’s a yes, seeing it written down would upset him so just wondering what to expect from Social Security Scotland.

thank you.

ps if anyone knows rough estimate they are taking to turn these round that would be appreciated to