"BlackRock's six-digit numeric code (340965) is notably less circulated in public forums than three-letter ticker codes, slightly reducing discovery risk. However, finance-sector codes in NYC and SF see elevated scrutiny. "Medium-risk codes are subject to spot checks, especially during mid-week peak business travel, with properties in major metropolitan areas being the most likely to ask for a badge." BlackRock's NYC concentration and premium rate level keep this firmly at Medium. Numeric codes also trigger less "code sharing" behavior, reducing overall exposure volume."

"I work as a consultant and frequently ask for and use my client's rates (at their insistence, since I will be billing them back). I have been asked for ID maybe one time in 15 since February, when it was announced in this forum that rates would be ID'ed."

"I have been asked to show some proof couple of times. I normally show my corp id but credit card with employers name on it has worked, too. As would probably just showing my laptop with employer e-mail account or whatever. My impression has been they are happy with just about anything that proves I'm working for the company whose rate I use and why wouldn't they."