"This means you should wear what you always wear"
Reminds me of a couple of instances from my past.
First was a story of when INMOS was bought by ThornEMI there was a demo to be done at Thorn's HQ and the INMOS person to do it asked what he should wear - he was told to come in normal work clothes .... apparently turned out a rainbow stripe sweater was a new experience for staff at Thorn HQ!
Then a few years later we had a meeting with "important people" from HP who were presenting the architecture of a processor we might colaborate on and we were all instructured to wear suits. So we all turned up to meeting room in suits and (while admitedly a couple of senior HP management came in jackets and ties) we waited for the HP architrects to arrive (their flight was delayed) ... and they were, not unexpectedly, all wearing jeans and t-shirts!