Agreement to sale has no mention of undivided share of land

I have booked a flat with a premium builder to my surprise he is offering me an agreement of sale that does not have any mention of undivided share of land though there is a mention of proportional undivided interest in a common area( agreement has no clarity on the common area or basis for computation) . They make it clear nothing will be mentioned even in the sale deed. The legal team is stating nothing to worry - A) common area according to RERA and Karnataka apartment owners act includes land . The land is automatically transferred to the owners / association even if this is not expressly mentioned B) the area will be determined on completion of the project and mention in deed to declaration on formation of the association . C) I checked most the builders in bangalore are very clear in providing UDS. They have no credible answer on why they would not provide it. The building plan is approved). Appreciate if some body can provide me inputs if this is fine.