Is "Ditra" some kind of modified thin-set?
You aren't planning on setting tile directly to any kind of wood, are you?
You didn't learn how to set tile from a "Time Life" book, or Home Depot class, because if so you've probably got some very WRONG information that could have less than optimal results. Such as, never set tile directly to any kind of wood. Use a good underlayment instead. I use only hardiboard. You thinset the HBoard, then use ring-shank nails to fasten it. (Hardi-Screws are an expensive joke. There's a retard at Hardiboard, Inc. that needs to be fired, because I'm not buying their stock until the stop selling those shitty excuses for screws. I've got brand-new white porcelain tile permanently spattered with molten debris from grinding the heads of their screws down because they won't counter-sink into the hardiboard; the phillips head on the screwgun breaks first, or the phillips head spins out, wallers and you can't get it to go in OR out.)
Ring shank nails are almost as good as screws (which aren't really needed), are cheaper, faster, more reliable and less hassle. Watch out for your thumb. There's a two-step method for nailing them which will save you some pain and possibly an ER visit. (Amazing how instructive pain can be, and inspirational. Even a dullard can figure out some varient of this two-step nail hammering process after a visit to the ER. Someone should tell our President this. But I digress...)
Set Hardiboard to plywood with thinset and ringshank nails, set tile to hardiboard with thinset. And don't waste your money on the high-bond stuff that costs $30.00 a bag. The mid-grade $12.00 a bag stuff is good enough.
Also, if anyone has told you anything that contradicts what I have said, you should also discount anything and everything else they may have said as being potentially wrong. They could be "right" in that what they have said may be correct, but they can't be right in the sense that they actually KNOW anything, because all they know is what someone else has told them, and "someone else" may know as little as the person that they told. Short words travel faster in the game of Operator. Long concepts have to be gotten directly from the source. Anyone that behaves as if this is not true is arrogant, and too stupid to recognize their limitations. Also, people that recognize their limitations say less than people that do not, and yet they know more. You should listen to them, and ignore everyone else.
Lady calls asking if I would be appreciative of the favor of having the opportunity to underbid the Mexican guy that was going to set her living room floor tile for $300 and 2 6-packs of beer. In the middle of bestowing upon me all her worldly wisdom that she learned from the lap of her long-dead and retarded father, she said "All you do is find the center of the room, set a piece of tile there and then work outward, right? Anyone can do it."
I said, "No ma'am, that's the exact opposite of how you are supposed to lay-out a room. The only people that do it that way are the people that haven't got a clue about what they are doing. Usually drunks that still live with their Mother's and are only interested in working for beer money. (I just described her son, who told her how the tile should be set.)
Unfortunately, I did not get that job, through no fault or deficiency of my own.