As always, I caveat a variable with, it works at the moment, don't be surprised if it's removed in the future.
Here's what I keep in my env file to remind what it is and does:
#Siemens' best practice recommendation for creating drawings is to create
#master model drawings. This means the master model resides in one part file
#while the drawing resides in another part file. The drawing file references
#the data in the master model file. Prior to NX 8, when a base view was added
#to the drawing, the referenced view would default to the model view from the
#current drawing file. This is counter to the master model best practice. So
#a change to the base view dialog was made in NX 8 to default to the views in
#the master model. Users should be aware of this change and understand the
#referenced views and geometry are now of the master model and not what is in
#the drawing file. If users want the pre-NX 8 behavior, they can change the
#part option to use the current drawing file and not the master model file or if
#they wish to have this as the default for the system they can set the
#environment variable:
NX_MASTER_MODEL_DWNG_DEFAULT_TO_ROOT_PART=1
Anthony Galante
Senior Support Engineer

NX3 to NX10 with almost every MR (21versions)