Watch the Shift Slide online guitar lesson by Chris Buono from 60 Electric Guitar Techniques You MUST Know
A shift slide is another sliding technique that involves an initial note or chord to be played followed by the fret hand moving that note or chord up or down the neck while it rings to its destination note. The key difference between shift slides and legato slides is the destination note is played again afterwards. Don't let anyone tell you anything different.
Looking for inspiration? Tony Iommi and the opening riff to "Iron Man". The slide from B5 to D5 is a textbook shift slide.