question about lot-line windows

I am curious about any NYC regs. covering new construction adjacent to residential lot-line windows. The case in point involves a midtown street-level parking through-lot next to a 15-story building of loft residences. Each loft residence has multiple lot-line windows that overlook the parking lot. If a developer sought to make parking lot into new high-rise (crazy notion, I know!), is there a reg. stating the minimum distance that must separate a new structure from the windows of an existing building? This residential building has no setbacks on the parking lot side – it’s a sheer vertical wall.

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