I'm noticing this more and more in job postings. People want me to be proficient or expert or skilled in a long list of design apps, and usually at the top of the list is Quark and InDesign. I've used InDesign for years. I've had formal schooling on it. I know lots about it. I've never been exposed to Quark aside from reading about it. My question is: what am I missing exactly (by not being familiar with Quark)? Would I be limited to using which ever was available any given day, as opposed to just using the one of my choice? Should I be expected to use both because of the limitations of either? Is there interoperability between the two that I don't know about? I'm not looking to revive the battle between the two products to determine which is best, but rather could you please help me understand why so many potential employers are saying one and the other; not one or the other?