It used to be that at every show your seating assignment was written on blank, white index cards when you checked in, and so it was easy for crafty crashers to simply write "S" or "ST" on a card from Duane Reade across the street, and jump into the standing line of a show without any problems. But this season, maybe because of all the slashed guest lists, the PR's have caught on. At Erin Fetherston last night (which is a much more crashed show than people realize), the BPCM girls handed you your seating assignment on oversized index cards, the kind no one ever buys. At Y-3 earlier in the day, assignments were scrawled on blue cards, which we'd never seen before. And at Alexander Wang on Saturday, the security was the tightest we'd ever seen at any show, with seating assignments on neon green cards, flashlight-wielding security guards blocking off the seating section and actually reading your assignment before letting you in at all (the standing section was not let in, and they basically stood in Siberia). But no show is going to have this new security quite like Marc Jacobs tonight. What was once the most easily crashed show - you would always see throngs of students just rushing the door with the other 2,000 guests - is now totally uncrashable, as KCD has drawn up such a short invite list that most of the show is mono-rowed, meaning you would easily be picked out just by showing your uninvited face. Just a sign of that more serious and somber Fashion Week everybody's been describing so far.