NX is a version release which combines the excellence from both the traditional I-deas product line and the Unigraphics product line to create a product with superior productivity.
Since 2001, UGS have been planning to move I-DEAS users to a new next level hence releasing NX1 till NX4 today.
Last version of Unigraphics and I-DEAS are v19 and V12 respectively.