Just a question: Previously within practice I've seen such as coded door locks (i.e. you have to key in a 4-digit code to open the door) used predominantly to prevent a person leaving a building (often referred to as an 'anti-wandering device' rather than 'lock' - more p.c. I suppose... now, at University, I was told that you had to have the number written nearby, so that anyone wishing to leave could do so providing they read and retained that info. Now all this 'what you have to' type of stuff is all well and good, but does anyone have any info as to the law re: this? Anything documented? Any links to relevant info re: this appreciated. N.