Straight into stack?

I just moved into a new apartment in new york city and im trying to redo my bathroom. I was told i can only replace the toilet with a few choices because unlike most toilets, this one plugs directly into the stack of the building (as opposed to what i dont know) or something like this. Has anybody heard of this type of hookup situation? If so am i really that limited with a replacement? Thanks.

Edit- from reading in this forum i think i have a rear discharge toilet? Does this sound right?

Sounds like you have a floor mounted rear discharge toilet. They are available....American Standard Yorkville comes to mind. Your choices will be somewhat limited, and the are pricey.

yup, ive been readding and it seems that there are very few choices for these. Do you know of any that are the most "modern" looking of them? The only ones i have found are the gerber and yorkville and both are quite big and ugly(in my opinion.) Im looking for a toto look.