b building is determined based on a series of scopes of work under the checklist, and that's under sequa to review the properties. >> okay. >> there's some projects, like, replacing a window, that doesn't matter. it could stay a b, and we'll review it, but if somebody wants to demolish a building, that sends them down a path that now we would know up front, well, that building was never resourced to begin with. >> so these are the categorical exemptions pursuant to sequa you're talking about, or they are specific -- >> could be many things. >> could be both? >> can i jump in? we do this every day. >> so, basically, if we have a project, you're going to do this work one way or another, either by submitting a supplemental form, which is part of the environmental evaluation. if -- and the trigger would be something that motio modifies te exterior of the building in some way other than replacing a window or, you know, changing your roofing material. if you're going to do an addition to the building and a substantial addition, you have to do an hre. >> but what about changing all the windows?