Hi Murphys,Originally posted in cdnusers.org by cadpro2k
No, splits commonly WERE done only in Negative planes going way back. Positive planes were seldom used because of the file size they generate. With more and more memory now-a-daz that's not a limitation.
Negative planes, and anti-etch will provide you the plane splits you require. You still need to define the shapes on the NEG layers for allegro to see connections, and it' very easy to do. Give it a try. You never know, you might like it.
I even think there's a video on Sourcelink showing how to create NEG planes and plane splits. :)