Some events publish guest list rules. They appear on the event page above the join form and in your confirmation email. Read them before you head out.
Arrive by times
These are arrival cutoffs based on how you describe yourself. Arrive before the time shown for your category. After that time, the door team sees a warning that you are late and may not honour your place on the list.
The door scanner flags late arrivals automatically, so turning up past your cutoff is never a technicality that slips through.
Dress code
This states what the venue expects you to wear. If the door enforces it strictly, the event page is where you will be told.
House rules
Anything else the venue wants you to know — table etiquette, ID requirements, re-entry policy and similar conditions.