Back around 2001or so, an E/A/C firm of about 237 people with three offices decided to nail this topic down.
So, a very diverse group of employees formed a "Physical Appearance" task force and went at it.
Once drafted, it was sent to all employees . . .who were encouraged to take it home . . . for their input and advice.
Not only did it include what clothing to wear for various functions, it also included tattoos, face jewelry, hairstyles, and color, just about everything that was identified as a concern for any and all employees.
Once edited and re-issued, it was released and became that firm's go-to book for the obvious questions that might arise.
Everyone had an opportunity to input, review, evaluate, revise, comment, etc., before its approval and release.
p.s. Before reacting to this historical milestone for an E/A/C firm, recall it was
some 20 years/ two decades ago.